21975866165 has 64 divisors (see below), whose sum is σ = 31081881600. Its totient is φ = 14743814400.

The previous prime is 21975866131. The next prime is 21975866167. The reversal of 21975866165 is 56166857912.

It is not a de Polignac number, because 21975866165 - 2⁸ = 21975865909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21975866165.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21975866167) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 21523355 + ... + 21524375.

It is an arithmetic number, because the mean of its divisors is an integer number (485654400).

Almost surely, 2^21975866165 is an apocalyptic number.

It is an amenable number.

21975866165 is a deficient number, since it is larger than the sum of its proper divisors (9106015435).

21975866165 is a wasteful number, since it uses less digits than its factorization.

21975866165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1578.

The product of its digits is 5443200, while the sum is 56.

The spelling of 21975866165 in words is "twenty-one billion, nine hundred seventy-five million, eight hundred sixty-six thousand, one hundred sixty-five".