256866 has 16 divisors (see below), whose sum is σ = 530688. Its totient is φ = 82800.

The previous prime is 256831. The next prime is 256873. The reversal of 256866 is 668652.

It is a nialpdrome in base 8.

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 7 ways as a sum of consecutive naturals, for example, 505 + ... + 876.

It is an arithmetic number, because the mean of its divisors is an integer number (33168).

2²⁵⁶⁸⁶⁶ is an apocalyptic number.

256866 is an abundant number, since it is smaller than the sum of its proper divisors (273822).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256866 is a wasteful number, since it uses less digits than its factorization.

256866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1417.

The product of its digits is 17280, while the sum is 33.

The square root of 256866 is about 506.8194944948. The cubic root of 256866 is about 63.5675598971.

The spelling of 256866 in words is "two hundred fifty-six thousand, eight hundred sixty-six".