21252591997920 has 384 divisors, whose sum is σ = 78371774208000. Its totient is φ = 5368317825024.

The previous prime is 21252591997909. The next prime is 21252591997933. The reversal of 21252591997920 is 2979919525212.

21252591997920 is a `hidden beast` number, since 2 + 1 + 2 + 525 + 9 + 19 + 9 + 7 + 92 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 9195756 + ... + 11272404.

It is an arithmetic number, because the mean of its divisors is an integer number (204093162000).

Almost surely, 2^{21252591997920} is an apocalyptic number.

21252591997920 is a gapful number since it is divisible by the number (20) 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 21252591997920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39185887104000).

21252591997920 is an abundant number, since it is smaller than the sum of its proper divisors (57119182210080).

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

21252591997920 is a wasteful number, since it uses less digits than its factorization.

21252591997920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2076799 (or 2076785 counting only the distinct ones).

The product of its (nonzero) digits is 18370800, while the sum is 63.

The spelling of 21252591997920 in words is "twenty-one trillion, two hundred fifty-two billion, five hundred ninety-one million, nine hundred ninety-seven thousand, nine hundred twenty".