256731 has 4 divisors (see below), whose sum is σ = 342312. Its totient is φ = 171152.

The previous prime is 256723. The next prime is 256757. The reversal of 256731 is 137652.

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

It is a cyclic number.

It is not a de Polignac number, because 256731 - 2³ = 256723 is a prime.

It is a super-2 number, since 2×256731² = 131821612722, which contains 22 as substring.

It is an Ulam number.

It is a D-number.

256731 is a lucky 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 256731.

It is not an unprimeable number, because it can be changed into a prime (256721) 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, 42786 + ... + 42791.

It is an arithmetic number, because the mean of its divisors is an integer number (85578).

2²⁵⁶⁷³¹ is an apocalyptic number.

256731 is a deficient number, since it is larger than the sum of its proper divisors (85581).

256731 is an equidigital number, since it uses as much as digits as its factorization.

256731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85580.

The product of its digits is 1260, while the sum is 24.

The square root of 256731 is about 506.6862934795. The cubic root of 256731 is about 63.5564216325.

The spelling of 256731 in words is "two hundred fifty-six thousand, seven hundred thirty-one".