23 (number)

This article is about the number 23. For other uses, see 23 (disambiguation).

← 22 23 24 →
← 20 21 22 23 24 25 26 27 28 29 → List of numbers Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	twenty-three
Ordinal	23rd (twenty-third)
Numeral system	trivigesimal
Factorization	Prime
Divisors	1, 23
Greek numeral	ΚΓ´
Roman numeral	XXIII
Binary	101112
Ternary	2123
Senary	356
Octal	278
Duodecimal	1B12
Hexadecimal	1716

23 (twenty-three) is the natural number following 22 and preceding 24.

In mathematics

• Twenty-three is the ninth prime number, the smallest odd prime that is not a twin prime. Twenty-three is also the fifth factorial prime, the second Woodall prime. It is an Eisenstein prime with no imaginary part and real part of the form 3n − 1.

• The fifth Sophie Germain prime and the fourth safe prime, 23 is the next to last member of the first Cunningham chain of the first kind to have five terms (2, 5, 11, 23, 47). Since 14! + 1 is a multiple of 23 but 23 is not one more than a multiple 14, 23 is a Pillai prime. 23 is the smallest odd prime to be a highly cototient number, as the solution to x − φ(x) for the integers 95, 119, 143, 529.

• 23 is the first prime p for which unique factorization of cyclotomic integers based on the pth root of unity breaks down.

• The sum of the first 23 primes is 874, which is divisible by 23, a property shared by few other numbers.

• In the list of fortunate numbers, 23 occurs twice, since adding 23 to either the fifth or eighth primorial gives a prime number (namely 2333 and 9699713).

• 23 also has the distinction of being one of two integers that cannot be expressed as the sum of fewer than 9 cubes of positive integers (the other is 239). See Waring's problem.

• 23 is a Wedderburn–Etherington number. The codewords in the perfect (non-extended) binary Golay code are of size 23.

• According to the birthday paradox, in a group of 23 (or more) randomly chosen people, the probability is more than 50% that some pair of them will have the same birthday. A related coincidence is that 365 times the natural logarithm of 2, approximately 252.999, is very close to the number of pairs of 23 items, 253.

• In base 10, 23 is the second Smarandache–Wellin prime, as it is the concatenation of the base 10 representations of the first two primes (2 and 3) and is itself also prime. It is also a happy number in base 10. 23! is 23 digits long in base 10. There are only three other numbers that have this property: 1, 22, and 24.

• The natural logarithms of all positive integers lower than 23 are known to have binary BBP-type formulae.

• 23 is the smallest prime number p such that the largest consecutive pair of p-smooth numbers is the same as the largest consecutive pair of (p − 1)-smooth numbers, as given in the On-Line Encyclopedia of Integer Sequences sequence A228611. That is, the largest consecutive pair of 23-smooth numbers, (11859210, 11859211), is the same as the largest consecutive pair of 22-smooth numbers, and 23 is the smallest prime for which this is true.

• 23 is the smallest positive solution to Sunzi's original formulation of the Chinese remainder theorem.

In science and technology

• The atomic number of vanadium.
• The atomic mass number of the stable isotope of sodium.
• Normal human sex cells have 23 chromosomes. Other human cells have 46 chromosomes, arranged in 23 pairs.
• Scientific notation for the Avogadro constant is written as 6.02214179(30)×10²³ mol⁻¹.
• 23 is the width of the Arecibo message, sent to space in search for extraterrestrial intelligence.
• 23 is the TCP/IP port used for telnet and is the default for the telnet command.

In religion

• Psalm 23, also known as the Shepherd Psalm, is possibly the most quoted and best known Psalm. Psalms is also the 23rd book in the Douay–Rheims Bible.
• In Islam, the Qur'an was revealed in a total of 23 years to Prophet Muhammed.
• Muslims believe the first verses of the Qur'an were revealed to the Islamic prophet Muhammad on the 23rd night of the 9th Islamic month.
• Principia Discordia, the sacred text of Discordianism, holds that 23 (along with the discordian prime 5) is one of the sacred numbers of Eris, goddess of discord.

In popular culture

Music

• Alfred Harth uses the number 23 in his artist name Alfred 23 Harth, or A23H, since the year 1+9+8+5 = 23.
• Several songs and albums use the number 23 as their titles, including Tristan Prettyman's debut album, the eleventh song from Tool's fourth full-length studio album 10,000 Days, "Viginti Tres" (Latin for twenty-three).
• Blonde Redhead have the album '23' and the song with the same name.
• Jimmy Eat World's song "23" appeared on their album Futures. The number also appears in the songs "Christmas Card" and "12."23".95" as well as on some items of clothing produced by the band.
• Four tet and Yellowcard both have songs titled "Twenty-Three".
• The Posies have a record called Dear 23
• The Church's 2009 studio album is called "Untitled 23"
• Spiral Tribe From its inception, the group was obsessed by the number 23. Members sometimes recorded under the moniker of SP23, and the record label itself was called Network 23.
• Carbon Based Lifeforms released a 2011 album titled "Twentythree."
• Noah23 has several albums which reference the number 23.
• Luna's song "23 Minutes in Brussels" (featuring Tom Verlaine) appears on their album "Penthouse".
• The composer Alban Berg had a particular interest in the number 23, using it to structure several works. Various suggestions have been made as to the reason for this interest: that he took it from the Biorhythms theory of Wilhelm Fliess, in which a 23-day cycle is considered significant, or because he first suffered an asthma attack on 23rd of the month.
• 23 is a single by Mike Will Made-It released in 2013 featuring Miley Cyrus, Wiz Khalifa, and Juicy J.
• On the cover of The Beatles' 1969 album Yellow Submarine the number 23 is displayed on the chest of one of the Blue Meanies.
• The number 23 is used by the Spiral Tribe free party sound system. Sometimes it's used to discretely mark the spots of a freetekno rave. Some of the members of the Spiral Tribe are also known as Network 23,

Film and television

• 23 is a German film about Karl Koch.
• The Number 23 is a 2007 film starring Jim Carrey about a man who becomes obsessed with the 23 enigma.
• The 1980s TV series Max Headroom was set at Network 23.
• In The Matrix Reloaded, the Architect tells Neo it is of utmost importance to choose 23 people to repopulate Zion.
• In Jeepers Creepers, the Creeper appears every 23 years for 23 days to feast on human flesh.
• As revealed in Japanese film L: Change the World, 23 is the maximum number of days a person may live before he dies by the cause of writing his name in Death Note. Main protagonist L of the film L: Change the World, signs his name in Death Note so to die after 23 days.
• In The Big Lebowski, the main characters deliberately use only lane 23 at the bowling alley.

Other fields

• 23 skidoo (phrase) (sometimes 23 skiddoo) is an American slang phrase popularized during the early 20th century. 23 skidoo has been described as "perhaps the first truly national fad expression and one of the most popular fad expressions to appear in the U.S".
• The 23 Enigma plays a prominent role in the plot of the Illuminatus! Trilogy by Robert Shea and Robert Anton Wilson.
• The 23, in South Africa, refers to the 23 conscientious objectors who publicly refused to do military service in the Apartheid army in 1987. The following years the number increased to 143 (in 1988) and 771 (in 1989), with Apartheid being dismantled from 1990 onwards.
• Julius Caesar was stabbed 23 times.
• In The Legend of Zelda: Ocarina of Time, within the first dungeon, a deku scrub states "The order is...2 3 1. Twenty-three is number one!" as a hint to defeating his brethren deeper in the dungeon.
• X-23 is a character in the Marvel Universe. She is named for being the 23rd attempt to create a female genetic twin of Wolverine after attempts to create a male clone failed.
• In Blizzard Entertainment's team-based first-person shooter video game, Overwatch, and in the now finished Alternate Reality Game (ARG) based on the Offense hero, Sombra, the number 23 was important. Sombra ended up being the 23rd hero in Overwatch, hence the reference to the number.

External links

• Article in the British newspaper The Mirror regarding the power of the number 23
• A Portal for 23 Knowledge and Culture
• 23 facts, 23 images, 23 gallery, and links to other 23's