256865 has 16 divisors (see below), whose sum is σ = 362880. Its totient is φ = 170880.

The previous prime is 256831. The next prime is 256873. The reversal of 256865 is 568652.

It is a happy number.

It is not a de Polignac number, because 256865 - 2⁶ = 256801 is a prime.

It is a Curzon number.

It is a nialpdrome in base 8.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 256865.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1346 + ... + 1524.

It is an arithmetic number, because the mean of its divisors is an integer number (22680).

2²⁵⁶⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

256865 is a deficient number, since it is larger than the sum of its proper divisors (106015).

256865 is a wasteful number, since it uses less digits than its factorization.

256865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232.

The product of its digits is 14400, while the sum is 32.

The square root of 256865 is about 506.8185079493. The cubic root of 256865 is about 63.5674774058.

The spelling of 256865 in words is "two hundred fifty-six thousand, eight hundred sixty-five".