21691851208800 has 144 divisors (see below), whose sum is σ = 73676844380160. Its totient is φ = 5532993917440.

The previous prime is 21691851208787. The next prime is 21691851208829. The reversal of 21691851208800 is 880215819612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 196428960 + ... + 196539359.

It is an arithmetic number, because the mean of its divisors is an integer number (511644752640).

Almost surely, 2^{21691851208800} is an apocalyptic number.

21691851208800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21691851208800 is an abundant number, since it is smaller than the sum of its proper divisors (51984993171360).

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

21691851208800 is a wasteful number, since it uses less digits than its factorization.

21691851208800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392968365 (or 392968352 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 51.

The spelling of 21691851208800 in words is "twenty-one trillion, six hundred ninety-one billion, eight hundred fifty-one million, two hundred eight thousand, eight hundred".