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Cardinal | twenty-five | |||
Ordinal | 25th (twenty-fifth) |
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Factorization | 52 | |||
Divisors | 1, 5, 25 | |||
Roman numeral | XXV | |||
Binary | 110012 | |||
Ternary | 2213 | |||
Quaternary | 1214 | |||
Quinary | 1005 | |||
Senary | 416 | |||
Octal | 318 | |||
Duodecimal | 2112 | |||
Hexadecimal | 1916 | |||
Vigesimal | 1520 | |||
Base 36 | P36 |
25 (twenty-five) is the natural number following 24 and preceding 26.
It is a square number, being 52 = 5 × 5. It is one of two two-digit numbers whose square and higher powers of the number also ends in the same last two digits, e.g. 252 = 625, the other is 76. It is the smallest square that is also a sum of two (non-zero) squares: 25 = 32 + 42. Hence it often appears in illustrations of the Pythagorean theorem.
25 is a centered octagonal number, a centered square number, and an automorphic number.
25 percent (%) is equal to 1/4.
25 has an aliquot sum of 6 and number 6 is the first (or smallest) number to have an aliquot sequence that does not culminate in 0 through a prime. 25 is the aliquot sum of three integers; 95, 119, and 143. Twenty-five is the second composite member of the 6-aliquot tree.
It is the smallest base 10 Friedman number as it can be expressed by its own digits: 52.
It is also a Cullen number. 25 is the smallest pseudoprime satisfying the congruence 7n = 7 mod n.
25 is the smallest aspiring number — a composite non-sociable number whose aliquot sequence does not terminate.