656624640 has 352 divisors, whose sum is σ = 2490200064. Its totient is φ = 144506880.

The previous prime is 656624623. The next prime is 656624651. The reversal of 656624640 is 46426656.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3333022 + ... + 3333218.

It is an arithmetic number, because the mean of its divisors is an integer number (7074432).

Almost surely, 2^656624640 is an apocalyptic number.

656624640 is a gapful number since it is divisible by the number (60) 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 656624640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1245100032).

656624640 is an abundant number, since it is smaller than the sum of its proper divisors (1833575424).

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

656624640 is a wasteful number, since it uses less digits than its factorization.

656624640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263 (or 245 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 39.

The square root of 656624640 is about 25624.6880956627. The cubic root of 656624640 is about 869.1719959378.

The spelling of 656624640 in words is "six hundred fifty-six million, six hundred twenty-four thousand, six hundred forty".