21641404656 has 40 divisors (see below), whose sum is σ = 55993451904. Its totient is φ = 7202641600.

The previous prime is 21641404627. The next prime is 21641404679. The reversal of 21641404656 is 65640414612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 317370 + ... + 379481.

Almost surely, 2^21641404656 is an apocalyptic number.

It is an amenable number.

21641404656 is an abundant number, since it is smaller than the sum of its proper divisors (34352047248).

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

21641404656 is a wasteful number, since it uses less digits than its factorization.

21641404656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 697509 (or 697503 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

The spelling of 21641404656 in words is "twenty-one billion, six hundred forty-one million, four hundred four thousand, six hundred fifty-six".