251566560 has 480 divisors, whose sum is σ = 1053803520. Its totient is φ = 55323648.

The previous prime is 251566559. The next prime is 251566603. The reversal of 251566560 is 65665152.

It is a happy number.

251566560 is a `hidden beast` number, since 25 + 15 + 66 + 560 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a super-2 number, since 2×251566560² = 126571468220467200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

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 79 ways as a sum of consecutive naturals, for example, 4263811 + ... + 4263869.

It is an arithmetic number, because the mean of its divisors is an integer number (2195424).

Almost surely, 2^251566560 is an apocalyptic number.

251566560 is a gapful number since it is divisible by the number (20) 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 251566560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (526901760).

251566560 is an abundant number, since it is smaller than the sum of its proper divisors (802236960).

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

251566560 is a wasteful number, since it uses less digits than its factorization.

251566560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The square root of 251566560 is about 15860.8499141755. The cubic root of 251566560 is about 631.2736139910.

The spelling of 251566560 in words is "two hundred fifty-one million, five hundred sixty-six thousand, five hundred sixty".