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Five

← 4 5 6 →
−1 0 1 2 3 4 5 6 7 8 9
Cardinal five
Ordinal 5th
(fifth)
Numeral system quinary
Factorization prime
Prime 5
Divisors 1, 5
Roman numeral V
Roman numeral (unicode) Ⅴ, ⅴ
Greek prefix /
Latin prefix //
Binary 1012
Ternary 123
Quaternary 114
Quinary 105
Senary 56
Octal 58
Duodecimal 512
Hexadecimal 516
Vigesimal 520
Base 36 536
Greek ε (or Ε)
Arabic & Kurdish ٥
Persian ۵
Urdu ۵
Ge'ez
Bengali
Kannada
Punjabi
Chinese numeral 五,伍
Korean 다섯,오
Devanāgarī (panch)
Hebrew ה (Hey)
Khmer
Telugu
Malayalam
Tamil

5 (five /ˈfv/) is a number, numeral, and glyph. It is the natural number following 4 and preceding 6.

Five is the third prime number. Because it can be written as 221 + 1, five is classified as a Fermat prime; therefore a regular polygon with 5 sides (a regular pentagon) is constructible with compass and unmarked straightedge. 5 is the third Sophie Germain prime, the first safe prime, the third Catalan number, and the third Mersenne prime exponent. Five is the first Wilson prime and the third factorial prime, also an alternating factorial. Five is the first good prime. It is an Eisenstein prime with no imaginary part and real part of the form 3n − 1. It is also the only number that is part of more than one pair of twin primes. Five is a congruent number.

Five is conjectured to be the only odd untouchable number and if this is the case then five will be the only odd prime number that is not the base of an aliquot tree.


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Wikipedia

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