256557220 has 24 divisors (see below), whose sum is σ = 539159544. Its totient is φ = 102548736.

The previous prime is 256557199. The next prime is 256557239. The reversal of 256557220 is 22755652.

It can be written as a sum of positive squares in 4 ways, for example, as 2090916 + 254466304 = 1446^2 + 15952^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30072 + ... + 37648.

It is an arithmetic number, because the mean of its divisors is an integer number (22464981).

Almost surely, 2^256557220 is an apocalyptic number.

256557220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256557220 is an abundant number, since it is smaller than the sum of its proper divisors (282602324).

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

256557220 is a wasteful number, since it uses less digits than its factorization.

256557220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9279 (or 9277 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 34.

The square root of 256557220 is about 16017.4036597696. The cubic root of 256557220 is about 635.4207804852.

The spelling of 256557220 in words is "two hundred fifty-six million, five hundred fifty-seven thousand, two hundred twenty".