21492972864 has 196 divisors, whose sum is σ = 69760856160. Its totient is φ = 6512866560.

The previous prime is 21492972847. The next prime is 21492972929. The reversal of 21492972864 is 46827929412.

It is a happy number.

21492972864 is a `hidden beast` number, since 2 + 1 + 492 + 9 + 72 + 86 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 21492972864.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 492277 + ... + 534155.

Almost surely, 2^21492972864 is an apocalyptic number.

21492972864 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 21492972864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34880428080).

21492972864 is an abundant number, since it is smaller than the sum of its proper divisors (48267883296).

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

21492972864 is an equidigital number, since it uses as much as digits as its factorization.

21492972864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41920 (or 41895 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 54.

The spelling of 21492972864 in words is "twenty-one billion, four hundred ninety-two million, nine hundred seventy-two thousand, eight hundred sixty-four".