21555564464 has 20 divisors (see below), whose sum is σ = 47730178704. Its totient is φ = 9238099008.

The previous prime is 21555564463. The next prime is 21555564469. The reversal of 21555564464 is 46446555512.

It is not an unprimeable number, because it can be changed into a prime (21555564461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96230087 + ... + 96230310.

Almost surely, 2^21555564464 is an apocalyptic number.

It is an amenable number.

21555564464 is an abundant number, since it is smaller than the sum of its proper divisors (26174614240).

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

21555564464 is a wasteful number, since it uses less digits than its factorization.

21555564464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192460412 (or 192460406 counting only the distinct ones).

The product of its digits is 2880000, while the sum is 47.

The spelling of 21555564464 in words is "twenty-one billion, five hundred fifty-five million, five hundred sixty-four thousand, four hundred sixty-four".