656226640 has 20 divisors (see below), whose sum is σ = 1525727124. Its totient is φ = 262490624.

The previous prime is 656226629. The next prime is 656226661. The reversal of 656226640 is 46622656.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 219750976 + 436475664 = 14824^2 + 20892^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-3 number, since 3×656226640³ (a number of 27 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 656226640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4101337 + ... + 4101496.

Almost surely, 2^656226640 is an apocalyptic number.

It is an amenable number.

656226640 is an abundant number, since it is smaller than the sum of its proper divisors (869500484).

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

656226640 is a wasteful number, since it uses less digits than its factorization.

656226640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8202846 (or 8202840 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 37.

The square root of 656226640 is about 25616.9209703274. The cubic root of 656226640 is about 868.9963499904.

The spelling of 656226640 in words is "six hundred fifty-six million, two hundred twenty-six thousand, six hundred forty".