256857 has 4 divisors (see below), whose sum is σ = 342480. Its totient is φ = 171236.

The previous prime is 256831. The next prime is 256873. The reversal of 256857 is 758652.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 256857 - 2¹² = 252761 is a prime.

It is a D-number.

256857 is a lucky number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (256877) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42807 + ... + 42812.

It is an arithmetic number, because the mean of its divisors is an integer number (85620).

2²⁵⁶⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

256857 is a deficient number, since it is larger than the sum of its proper divisors (85623).

256857 is an equidigital number, since it uses as much as digits as its factorization.

256857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85622.

The product of its digits is 16800, while the sum is 33.

The square root of 256857 is about 506.8106155163. The cubic root of 256857 is about 63.5668174675.

The spelling of 256857 in words is "two hundred fifty-six thousand, eight hundred fifty-seven".