256815 has 24 divisors (see below), whose sum is σ = 480480. Its totient is φ = 126144.

The previous prime is 256813. The next prime is 256831. The reversal of 256815 is 518652.

It is not a de Polignac number, because 256815 - 2¹ = 256813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256813) 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 23 ways as a sum of consecutive naturals, for example, 366 + ... + 804.

It is an arithmetic number, because the mean of its divisors is an integer number (20020).

2²⁵⁶⁸¹⁵ is an apocalyptic number.

256815 is a deficient number, since it is larger than the sum of its proper divisors (223665).

256815 is a wasteful number, since it uses less digits than its factorization.

256815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 463 (or 460 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 256815 is about 506.7691782261. The cubic root of 256815 is about 63.5633525670.

The spelling of 256815 in words is "two hundred fifty-six thousand, eight hundred fifteen".