21311954865600 has 672 divisors, whose sum is σ = 82657951219200. Its totient is φ = 4804546682880.

The previous prime is 21311954865599. The next prime is 21311954865613. The reversal of 21311954865600 is 656845911312.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 120098539 + ... + 120275861.

It is an arithmetic number, because the mean of its divisors is an integer number (123002903600).

Almost surely, 2^{21311954865600} is an apocalyptic number.

21311954865600 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 21311954865600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41328975609600).

21311954865600 is an abundant number, since it is smaller than the sum of its proper divisors (61345996353600).

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

21311954865600 is a wasteful number, since it uses less digits than its factorization.

21311954865600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177442 (or 177413 counting only the distinct ones).

The product of its (nonzero) digits is 1555200, while the sum is 51.

The spelling of 21311954865600 in words is "twenty-one trillion, three hundred eleven billion, nine hundred fifty-four million, eight hundred sixty-five thousand, six hundred".