256400520 has 64 divisors (see below), whose sum is σ = 770670720. Its totient is φ = 68242944.

The previous prime is 256400509. The next prime is 256400531. The reversal of 256400520 is 25004652.

It is an interprime number because it is at equal distance from previous prime (256400509) and next prime (256400531).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72309 + ... + 75771.

It is an arithmetic number, because the mean of its divisors is an integer number (12041730).

Almost surely, 2^256400520 is an apocalyptic number.

256400520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256400520 is an abundant number, since it is smaller than the sum of its proper divisors (514270200).

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

256400520 is a wasteful number, since it uses less digits than its factorization.

256400520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4094 (or 4090 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 256400520 is about 16012.5113583098. The cubic root of 256400520 is about 635.2913867187.

The spelling of 256400520 in words is "two hundred fifty-six million, four hundred thousand, five hundred twenty".