256861584 has 240 divisors, whose sum is σ = 881312640. Its totient is φ = 70156800.

The previous prime is 256861571. The next prime is 256861609. The reversal of 256861584 is 485168652.

256861584 is a `hidden beast` number, since 2 + 5 + 6 + 8 + 61 + 584 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2543134 + ... + 2543234.

It is an arithmetic number, because the mean of its divisors is an integer number (3672136).

Almost surely, 2^256861584 is an apocalyptic number.

256861584 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 256861584, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (440656320).

256861584 is an abundant number, since it is smaller than the sum of its proper divisors (624451056).

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

256861584 is a wasteful number, since it uses less digits than its factorization.

256861584 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183 (or 142 counting only the distinct ones).

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

The square root of 256861584 is about 16026.9018840199. The cubic root of 256861584 is about 635.6719561381.

The spelling of 256861584 in words is "two hundred fifty-six million, eight hundred sixty-one thousand, five hundred eighty-four".