21973218624 has 672 divisors, whose sum is σ = 81799151616. Its totient is φ = 5703229440.

The previous prime is 21973218611. The next prime is 21973218703. The reversal of 21973218624 is 42681237912.

21973218624 is a `hidden beast` number, since 2 + 1 + 9 + 7 + 3 + 2 + 18 + 624 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21973218624.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 57371137 + ... + 57371519.

It is an arithmetic number, because the mean of its divisors is an integer number (121724928).

Almost surely, 2^21973218624 is an apocalyptic number.

21973218624 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21973218624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40899575808).

21973218624 is an abundant number, since it is smaller than the sum of its proper divisors (59825932992).

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

21973218624 is a wasteful number, since it uses less digits than its factorization.

21973218624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 465 (or 443 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The spelling of 21973218624 in words is "twenty-one billion, nine hundred seventy-three million, two hundred eighteen thousand, six hundred twenty-four".