256657 has 4 divisors (see below), whose sum is σ = 267840. Its totient is φ = 245476.

The previous prime is 256651. The next prime is 256661. The reversal of 256657 is 756652.

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 a de Polignac number, because none of the positive numbers 2^k-256657 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (256651) 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, 5557 + ... + 5602.

It is an arithmetic number, because the mean of its divisors is an integer number (66960).

2²⁵⁶⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

256657 is a deficient number, since it is larger than the sum of its proper divisors (11183).

256657 is a wasteful number, since it uses less digits than its factorization.

256657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11182.

The product of its digits is 12600, while the sum is 31.

The square root of 256657 is about 506.6132647296. The cubic root of 256657 is about 63.5503145565.

The spelling of 256657 in words is "two hundred fifty-six thousand, six hundred fifty-seven".