21522261564 has 18 divisors (see below), whose sum is σ = 54403494600. Its totient is φ = 7174087176.

The previous prime is 21522261559. The next prime is 21522261577. The reversal of 21522261564 is 46516222512.

21522261564 is a `hidden beast` number, since 2 + 15 + 2 + 22 + 61 + 564 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 597840599 = 21522261564 / (2 + 1 + 5 + 2 + 2 + 2 + 6 + 1 + 5 + 6 + 4).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 298920264 + ... + 298920335.

Almost surely, 2^21522261564 is an apocalyptic number.

It is an amenable number.

21522261564 is an abundant number, since it is smaller than the sum of its proper divisors (32881233036).

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

21522261564 is a wasteful number, since it uses less digits than its factorization.

21522261564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 597840609 (or 597840604 counting only the distinct ones).

The product of its digits is 57600, while the sum is 36.

The spelling of 21522261564 in words is "twenty-one billion, five hundred twenty-two million, two hundred sixty-one thousand, five hundred sixty-four".