27 (number)

27 (twenty-seven) is the natural number following 26 and preceding 28. Twenty-seven is the smallest positive integer requiring four syllables to name in English, though it can be unambiguously defined in just two: "three cubed."

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Cardinal	27 twenty-seven
Ordinal	27th twenty-seventh
Factorization	$3^{3}\,\!$
Divisors	1, 3, 9, 27
Roman numeral	XXVII
Acrophonic Greek numeral	ΔΔΠΙΙ
Alphabetic Greek numeral	κζ´
Hebrew numeral	כז
Chinese numeral	二十七
Financial Chinese numeral	貳拾柒
Arabic numeral	٢٧
Binary (2)	11011
Negabinary (-2)	1101111
Ternary (3)	1000
Balanced ternary (-0+)	1000
Negaternary (-3)	12000
Quaternary (4)	123
Quinary (5)	102
Senary (6)	43
Septenary (7)	36
Octal (8)	33
Nonary (9)	30
Decimal (10)	27
Undecimal (11)	25
Duodecimal (12)	23
Tridecimal (13)	21
Hexadecimal (16)	1B
Vigesimal (20)	17
Quadrovigesimal (24)	13
Septemvigesimal (27)	10
Trigesimal (30)	R
Hexatridecimal (36)	R
Phinary (φ)	1010010.010101 111101.10111111

In mathematics

Twenty-seven is a perfect cube, being 3³ = 3 × 3 × 3. 27 is therefore the second smallest cube of a prime number. 27 is 3↑↑2 (using Knuth's up-arrow notation). There are exactly 27 straight lines on a cubic surface. 27 is also a decagonal number.

27 has an aliquot sum of 13 and is the first composite member of the 13-aliquot tree with the aliquot sequence (27,13,1,0)

In base 10, it is the first composite number not evenly divisible by any of its digits. It is the radix (base) of the septemvigesimal positional numeral system.

In a prime reciprocal magic square of the multiples of 1/7, the magic constant is 27.

It is the twenty-eighth (and twenty-ninth) digit in π. (3.141592653589793238462643383279...).

If you start counting with 0 it is considered one of few Self-Locating strings in pi.

In base 10, it is a Smith number and a Harshad number.

The unique simple formally real Jordan algebra, the exceptional Jordan algebra of self-adjoint 3 by 3 matrices of quaternions, is 27-dimensional.

In the Collatz conjecture (aka the "3n + 1 conjecture") a starting value of 27 requires 112 steps to reach 1, many more than any lower number.

In science

• The atomic number of cobalt.

Astronomy

• The Messier object M27, a magnitude 7.5 planetary nebula in the constellation Vulpecula, also known as the Dumbbell Nebula.
• The New General Catalogue object NGC 27, a spiral galaxy in the constellation Andromeda
• The Saros number of the solar eclipse series which began on -1993 March 9 and ended on -713 April 16. The duration of Saros series 27 was 1280.1 years, and it contained 72 solar eclipses. Further, the Saros number of the lunar eclipse series which began on -1944 July 17 and ended on -411 January 23. The duration of Saros series 27 was 1532.5 years, and it contained 86 lunar eclipses.
• The 27th moon of Jupiter is Sinope.
• Uranus has 27 moons

In religion

• There are a total of 27 books in the New Testament

In music

• The number of completed, numbered piano concertos by Wolfgang Amadeus Mozart and his birthday (27 January 1756).
• The age in years at which many famous rock/blues musicians died, sometimes referred to as the 27 Club, which includes Robert Johnson, Brian Jones, Janis Joplin, Jimi Hendrix, Jim Morrison, Chris Bell, D. Boon, and Kurt Cobain.
• A number which American parodist "Weird Al" Yankovic hides somewhere in many of his songs and videos. [1]
• The number of "8 by 10 color glossy pictures with circles and arrows" in the song Alice's Restaurant by Arlo Guthrie
• The punk rock band Lagwagon has a song entitled Twenty Seven on their album Double Plaidinum.
• The punk rock band Pinhead Gunpowder released a song entitled 27 on their album Shoot the Moon.
• The number 27 is featured in many song lyrics and titles penned by Ben Weasel, in his bands Screeching Weasel and The Riverdales.
• The number 27 is known as the East Bay Punk scene's number.
• The punk band The Adicts use the number 27 in many song lyrics and released an album entitled "27"
• "27" is name of a song by Scottish band Biffy Clyro from their 2002 album, Blackened Sky.
• The Dave Matthews Band began playing a song entitled #27 on their 2007 summer tour. It was also frequently played by Dave Matthews and Tim Reynolds on their past tour together.

In other fields

Twenty-seven is also:

• Gilles Villeneuve's famous Ferrari number now adopted by his son, Formula One World Champion Jacques Villeneuve in his NASCAR debut.
• The total number of letters in the Hebrew alphabet (22 regular letters and 5 final consonants)
• The number of letters in the Spanish alphabet
• The current number of Amendments to the United States Constitution.
• The modal age of the peak performance year for major league baseball position players, according to a commonly accepted theory by sabermetrician Bill James
• The code for international direct-dial phone calls to South Africa
• The designation (I-27) of a US interstate highway in Texas
• The designation (US 27) of a United States national highway from Fort Wayne, Indiana to Miami, Florida
• The name of a popular cigarette, Marlboro Blend No. 27
• The number of outs in a regulation Professional baseball game for each team.
• "The Bankers Case" on the U.S. Version of Deal or No Deal
• The subject of a joke on the Simpsons, where the following takes place. "Lisa, you are greater than or equal to any boy. You may only be 8, but your possibilities are infinite. 27"

Historical years

27 A.D., 27 B.C., 1927, 2027, etc.

References

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987), p. 106.

• Mystery of the number 27 - Large collection of 27 related trivia and facts.
• Prime Curios! 27 from the Prime Pages