51 (number)
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Cardinal | fifty-one | |||
Ordinal | 51st (fifty-first) |
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Factorization | 3 × 17 | |||
Divisors | 1, 3, 17, 51 | |||
Roman numeral | LI | |||
Binary | 1100112 | |||
Ternary | 12203 | |||
Quaternary | 3034 | |||
Quinary | 2015 | |||
Senary | 1236 | |||
Octal | 638 | |||
Duodecimal | 4312 | |||
Hexadecimal | 3316 | |||
Vigesimal | 2B20 | |||
Base 36 | 1F36 |
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Look up fifty-one in Wiktionary, the free dictionary. |
51 (fifty-one) is the natural number 51 following 50 and preceding 52.
In mathematics
Fifty-one is the 14th discrete semiprime and the 5th in the {3.q} semiprime family having the prime factors (3.17). The aliquot sum of 51 is 21, itself a discrete semiprime. 51 is the 4th member of the 11-aliquot tree with the sequence (51, 21, 11, 1, 0).
51 is a pentagonal number[1] as well as a centered pentagonal number[2] (one of the few numbers to be both) and an 18-gonal number[3] and a Perrin number.[4] It is also the 6th Motzkin number, telling the number of ways to draw non-intersecting chords between any six points on a circle's boundary, no matter where the points may be located on the boundary.[5]
Since the greatest prime factor of 512 + 1 = 2602 is 1301, which is substantially more than 51 twice, 51 is a Størmer number.[6] There are 51 different cyclic Gilbreath permutations on 10 elements,[7] and therefore there are 51 different real periodic points of order 10 on the Mandelbrot set.[8]
Since 51 is the product of the distinct Fermat primes 3 and 17, a regular polygon with 51 sides is constructible with compass and straightedge, the angle <templatestyles src="Sfrac/styles.css" />π/51 is constructible, and the number cos <templatestyles src="Sfrac/styles.css" />π/51 is expressible in terms of square roots.
In other fields
51 is:
- The atomic number of antimony
- The code for international direct dial phone calls to Peru
- The last possible television channel number in the UHF bandplan for American terrestrial television since December 31, 2011, when channels 52—69 were withdrawn
See also
- 51, a year in the Julian calendar
- List of highways numbered 51
- The model number of the P-51 Mustang WWII fighter aircraft
- Area 51, a parcel of U.S. military-controlled land in southern Nevada, apparently containing a secret aircraft testing facility
- Fifty-One Tales, part of the title of a collection of stories by Lord Dunsany
- "51st State", any future US state, usually referring to Washington D.C. or Puerto Rico. Occasionally used in commentary to refer to non-US entities (such as Alberta) adopting US-like policies or seeking to become part of the US.
- 51 (film), a 2011 American horror film
- "Fifty-One", an episode of Breaking Bad
- Pastis 51, often just called "51", is a brand of pastis owned by Pernod Ricard.
- Greg Murphy used "#51" for most of the seasons he raced in V8 Supercars
References
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