21012936189921 has 64 divisors (see below), whose sum is σ = 34695440640000. Its totient is φ = 12479920992000.

The previous prime is 21012936189859. The next prime is 21012936189929. The reversal of 21012936189921 is 12998163921012.

It is a happy number.

21012936189921 is a `hidden beast` number, since 2 + 1 + 0 + 12 + 9 + 3 + 618 + 9 + 9 + 2 + 1 = 666.

It is not a de Polignac number, because 21012936189921 - 2⁹ = 21012936189409 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21012936189929) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 23989171 + ... + 24849671.

It is an arithmetic number, because the mean of its divisors is an integer number (542116260000).

Almost surely, 2^{21012936189921} is an apocalyptic number.

It is an amenable number.

21012936189921 is a deficient number, since it is larger than the sum of its proper divisors (13682504450079).

21012936189921 is a wasteful number, since it uses less digits than its factorization.

21012936189921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 862951 (or 862945 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 54.

The spelling of 21012936189921 in words is "twenty-one trillion, twelve billion, nine hundred thirty-six million, one hundred eighty-nine thousand, nine hundred twenty-one".