49 (number)

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This article is about the number. For the steamboat, see Forty-Nine (steamboat).
← 48 49 50 →
Cardinal forty-nine
Ordinal 49th
Factorization 72
Divisors 1, 7, 49
Roman numeral XLIX
Binary 1100012
Ternary 12113
Quaternary 3014
Quinary 1445
Senary 1216
Octal 618
Duodecimal 4112
Hexadecimal 3116
Vigesimal 2920
Base 36 1D36

49 (forty-nine) is the natural number following 48 and preceding 50.

In mathematics[edit]

  • Forty-nine is the square of seven

The aliquot sum of forty-nine is 8, and this number has an aliquot sequence of (8, 7, 1, 0).

49 is the 8th composite number in the 7-aliquot tree.

The sum of the digits of the square of 49 (2401) is the square root of 49.

49 is the first square where the digits are squares. In this case 4 and 9 are squares.

It appears in the Padovan sequence, preceded by the terms 21, 28, 37 (it is the sum of the first two of these).[1]

Along with the number that immediately derives from it, 77, the only number under 3 digits not having its home prime known (as of late 2010).


The fraction 149 is a repeating decimal with a period of 42:

149 = 0.0204081632 6530612244 8979591836 7346938775 51 (42 repeating digits)

There are 42 (note that this number is the period) positive integers that are less than 49 and coprime to 49. Multiplying 020408163265306122448979591836734693877551 by each of these integers results in a cyclic permutation of the original number:

  • 020408163265306122448979591836734693877551 × 2 = 040816326530612244897959183673469387755102
  • 020408163265306122448979591836734693877551 × 3 = 061224489795918367346938775510204081632653
  • 020408163265306122448979591836734693877551 × 4 = 081632653061224489795918367346938775510204
  • ...

The repeating number can be obtained from 02 and repetition of doubles placed at two places to the right:

+                   ...

In chemistry[edit]

  • The atomic number of indium.
  • During the Manhattan Project, plutonium was also often referred to, simply, as "49". Number 4 was for the last digit in 94 (atomic number of plutonium) and 9 for the last digit in Pu-239, the weapon-grade fissile isotope used in nuclear bombs.[2][3]

In astronomy[edit]

In religion[edit]

In sports[edit]

See also 49er.

In music[edit]

See also: 49er
  • In Blues music lore, it was at the junction of US Highway 49 and 61 in Clarksdale, Mississippi, that legendary bluesman Robert Johnson sold his soul to the devil in return for fame and success. In later years Howlin’ Wolf immortalized the road in the song “Highway 49,” originally written by Big Joe Williams: “Long tall momma / She don’t pay me no mind / All she wanna do / Walk the Highway 49.”
  • ALSO: US Highway 49 continues from that infamous junction in Mississippi and through Helena-West Helena, Arkansas, home of legendary bluesmen Sonny Boy Williamson and renowned harmonica player Frank Frost who both began their careers on the King Biscuit Time radio show, the longest-running Blues radio show hosted by "Sunshine" Sonny Payne who, as of this entry (June 1, 2016) still hosts the daily radio show on KFFA-AM 1360 from the current studio in the Delta Cultural Center at the end of Cherry Street in downtown Helena, Arkansas. The radio show went on to inspire, arguably, one of the finest blues festivals, known world-wide by fans of early blues music as the annual King Biscuit Blues Festival on the river levee which holds the muddy waters of the mighty Mississippi River at bay a little over a hundred yards from the main stage of the festival, providing a down-home atmosphere that is second-to-none in the blues festivals held around the United States.[neutrality is disputed]

In other fields[edit]

Forty-nine is:


  1. ^ "Sloane's A000931 : Padovan sequence". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30. 
  2. ^ Hammel, E.F. (2000). "The taming of "49" — Big Science in little time. Recollections of Edward F. Hammel, pp. 2-9. In: Cooper N.G. Ed. (2000). Challenges in Plutonium Science" (PDF). Los Alamos Science 26 (1): 2–9. 
  3. ^ Hecker, S.S. (2000). "Plutonium: an historical overview. In: Challenges in Plutonium Science". Los Alamos Science 26 (1): 1–2. 
  4. ^ Audio commentary by Sherman Aexie and Sean Axmaker on the DVD of The Exiles