257 (number)
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|---|---|---|---|---|
| Cardinal | two hundred fifty-seven | |||
| Ordinal | 257th (two hundred and fifty-seventh) |
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| Factorization | 257 | |||
| Prime | yes | |||
| Roman numeral | CCLVII | |||
| Binary | 1000000012 | |||
| Ternary | 1001123 | |||
| Quaternary | 100014 | |||
| Quinary | 20125 | |||
| Senary | 11056 | |||
| Octal | 4018 | |||
| Duodecimal | 19512 | |||
| Hexadecimal | 10116 | |||
| Vigesimal | CH20 | |||
| Base 36 | 7536 | |||
257 is the natural number between 256 and 258. It is also a prime number.
In mathematics
257 is a prime number of the form 
specifically with n = 3, and therefore a Fermat prime. Thus a regular polygon with 257 sides is constructible with compass and unmarked straightedge. It is currently the second largest known Fermat prime. [1]
It is also a balanced prime,[2] an irregular prime,[3] a prime that is one more than a square,[4] and a Jacobsthal–Lucas number,[5]
There are exactly 257 combinatorially distinct convex polyhedra with eight vertices (or polyhedral graphs with eight nodes).[6]
In other fields
257 is the country calling code for Burundi. See List of country calling codes.
References
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- ↑ "Sloane's A006562 : Balanced primes", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ↑ "Sloane's A000928 : Irregular primes", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ↑ "Sloane's A002496 : Primes of form n^2 + 1", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ↑ "Sloane's A014551 : Jacobsthal-Lucas numbers", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ↑ "Sloane's A000944 : Number of polyhedra (or 3-connected simple planar graphs) with n nodes", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
