256581864 has 128 divisors (see below), whose sum is σ = 888652800. Its totient is φ = 66640320.

The previous prime is 256581841. The next prime is 256581869. The reversal of 256581864 is 468185652.

256581864 is a `hidden beast` number, since 2 + 5 + 6 + 581 + 8 + 64 = 666.

256581864 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (256581869) 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 31 ways as a sum of consecutive naturals, for example, 8919 + ... + 24345.

It is an arithmetic number, because the mean of its divisors is an integer number (6942600).

Almost surely, 2^256581864 is an apocalyptic number.

256581864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256581864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (444326400).

256581864 is an abundant number, since it is smaller than the sum of its proper divisors (632070936).

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

256581864 is a wasteful number, since it uses less digits than its factorization.

256581864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15460 (or 15450 counting only the distinct ones).

The product of its digits is 460800, while the sum is 45.

The square root of 256581864 is about 16018.1729295198. The cubic root of 256581864 is about 635.4411252752.

The spelling of 256581864 in words is "two hundred fifty-six million, five hundred eighty-one thousand, eight hundred sixty-four".