256561100 has 18 divisors (see below), whose sum is σ = 556737804. Its totient is φ = 102624400.

The previous prime is 256561099. The next prime is 256561117. The reversal of 256561100 is 1165652.

It is a self number, because there is not a number n which added to its sum of digits gives 256561100.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1282706 + ... + 1282905.

It is an arithmetic number, because the mean of its divisors is an integer number (30929878).

Almost surely, 2^256561100 is an apocalyptic number.

256561100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256561100 is an abundant number, since it is smaller than the sum of its proper divisors (300176704).

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

256561100 is a wasteful number, since it uses less digits than its factorization.

256561100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2565625 (or 2565618 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 256561100 is about 16017.5247775678. The cubic root of 256561100 is about 635.4239836955.

The spelling of 256561100 in words is "two hundred fifty-six million, five hundred sixty-one thousand, one hundred".