257905 has 4 divisors (see below), whose sum is σ = 309492. Its totient is φ = 206320.

The previous prime is 257903. The next prime is 257921. The reversal of 257905 is 509752.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 31329 + 226576 = 177^2 + 476^2 .

It is not a de Polignac number, because 257905 - 2¹ = 257903 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25786 + ... + 25795.

It is an arithmetic number, because the mean of its divisors is an integer number (77373).

2²⁵⁷⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

257905 is a deficient number, since it is larger than the sum of its proper divisors (51587).

257905 is an equidigital number, since it uses as much as digits as its factorization.

257905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51586.

The product of its (nonzero) digits is 3150, while the sum is 28.

The square root of 257905 is about 507.8434798242. The cubic root of 257905 is about 63.6531529603.

The spelling of 257905 in words is "two hundred fifty-seven thousand, nine hundred five".