20972137489921 has 32 divisors (see below), whose sum is σ = 22094689075200. Its totient is φ = 19878799861440.

The previous prime is 20972137489913. The next prime is 20972137490047. The reversal of 20972137489921 is 12998473127902.

It is a cyclic number.

It is not a de Polignac number, because 20972137489921 - 2³ = 20972137489913 is a prime.

It is a super-2 number, since 2×20972137489921² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20972137439921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2645654860 + ... + 2645662786.

It is an arithmetic number, because the mean of its divisors is an integer number (690459033600).

Almost surely, 2^{20972137489921} is an apocalyptic number.

It is an amenable number.

20972137489921 is a deficient number, since it is larger than the sum of its proper divisors (1122551585279).

20972137489921 is a wasteful number, since it uses less digits than its factorization.

20972137489921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10549.

The product of its (nonzero) digits is 27433728, while the sum is 64.

The spelling of 20972137489921 in words is "twenty trillion, nine hundred seventy-two billion, one hundred thirty-seven million, four hundred eighty-nine thousand, nine hundred twenty-one".