21681379965600 has 180 divisors, whose sum is σ = 79067777146974. Its totient is φ = 5781701306880.

The previous prime is 21681379965587. The next prime is 21681379965677. The reversal of 21681379965600 is 656997318612.

21681379965600 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 13 + 7 + 9 + 9 + 6 + 5 + 600 = 666.

21681379965600 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 14212025373456 + 7469354592144 = 3769884^2 + 2733012^2 .

It is a tau number, because it is divible by the number of its divisors (180).

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 29 ways as a sum of consecutive naturals, for example, 167229799 + ... + 167359398.

Almost surely, 2^{21681379965600} is an apocalyptic number.

21681379965600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21681379965600 is an abundant number, since it is smaller than the sum of its proper divisors (57386397181374).

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

21681379965600 is a wasteful number, since it uses less digits than its factorization.

21681379965600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334589229 (or 334589207 counting only the distinct ones).

The product of its (nonzero) digits is 29393280, while the sum is 63.

The spelling of 21681379965600 in words is "twenty-one trillion, six hundred eighty-one billion, three hundred seventy-nine million, nine hundred sixty-five thousand, six hundred".