21975109128 has 96 divisors (see below), whose sum is σ = 70212380160. Its totient is φ = 6076062720.

The previous prime is 21975109081. The next prime is 21975109147. The reversal of 21975109128 is 82190157912.

21975109128 is a `hidden beast` number, since 2 + 1 + 9 + 7 + 510 + 9 + 128 = 666.

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, 687625 + ... + 718872.

It is an arithmetic number, because the mean of its divisors is an integer number (731378960).

Almost surely, 2^21975109128 is an apocalyptic number.

21975109128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21975109128 is an abundant number, since it is smaller than the sum of its proper divisors (48237271032).

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

21975109128 is a wasteful number, since it uses less digits than its factorization.

21975109128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1406547 (or 1406540 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 45.

The spelling of 21975109128 in words is "twenty-one billion, nine hundred seventy-five million, one hundred nine thousand, one hundred twenty-eight".