251856864 has 216 divisors, whose sum is σ = 865316088. Its totient is φ = 71850240.

The previous prime is 251856859. The next prime is 251856889. The reversal of 251856864 is 468658152.

251856864 is a `hidden beast` number, since 2 + 518 + 56 + 86 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (216).

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 380694 + ... + 381354.

It is an arithmetic number, because the mean of its divisors is an integer number (4006093).

Almost surely, 2^251856864 is an apocalyptic number.

251856864 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 251856864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (432658044).

251856864 is an abundant number, since it is smaller than the sum of its proper divisors (613459224).

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

251856864 is an equidigital number, since it uses as much as digits as its factorization.

251856864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 700 (or 673 counting only the distinct ones).

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

The square root of 251856864 is about 15869.9988657845. The cubic root of 251856864 is about 631.5163473745.

The spelling of 251856864 in words is "two hundred fifty-one million, eight hundred fifty-six thousand, eight hundred sixty-four".