256397520 has 40 divisors (see below), whose sum is σ = 794833056. Its totient is φ = 68372608.

The previous prime is 256397513. The next prime is 256397551. The reversal of 256397520 is 25793652.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a congruent number.

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, 533922 + ... + 534401.

Almost surely, 2^256397520 is an apocalyptic number.

256397520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256397520 is an abundant number, since it is smaller than the sum of its proper divisors (538435536).

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

256397520 is a wasteful number, since it uses less digits than its factorization.

256397520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1068339 (or 1068333 counting only the distinct ones).

The product of its (nonzero) digits is 113400, while the sum is 39.

The square root of 256397520 is about 16012.4176812872. The cubic root of 256397520 is about 635.2889089785.

The spelling of 256397520 in words is "two hundred fifty-six million, three hundred ninety-seven thousand, five hundred twenty".