656921664 has 280 divisors, whose sum is σ = 2282675648. Its totient is φ = 182891520.

The previous prime is 656921623. The next prime is 656921669. The reversal of 656921664 is 466129656.

656921664 is a `hidden beast` number, since 6 + 569 + 21 + 6 + 64 = 666.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (656921669) 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 39 ways as a sum of consecutive naturals, for example, 1560174 + ... + 1560594.

Almost surely, 2^656921664 is an apocalyptic number.

656921664 is a gapful number since it is divisible by the number (64) 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 656921664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1141337824).

656921664 is an abundant number, since it is smaller than the sum of its proper divisors (1625753984).

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

656921664 is a wasteful number, since it uses less digits than its factorization.

656921664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495 (or 476 counting only the distinct ones).

The product of its digits is 466560, while the sum is 45.

The square root of 656921664 is about 25630.4831011825. The cubic root of 656921664 is about 869.3030327636.

The spelling of 656921664 in words is "six hundred fifty-six million, nine hundred twenty-one thousand, six hundred sixty-four".