21375561875856 has 80 divisors (see below), whose sum is σ = 58847060404224. Its totient is φ = 6670388086912.

The previous prime is 21375561875821. The next prime is 21375561875981. The reversal of 21375561875856 is 65857816557312.

It is a Harshad number since it is a multiple of its sum of digits (69).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 205926006 + ... + 206029781.

Almost surely, 2^{21375561875856} is an apocalyptic number.

It is an amenable number.

21375561875856 is an abundant number, since it is smaller than the sum of its proper divisors (37471498528368).

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

21375561875856 is a wasteful number, since it uses less digits than its factorization.

21375561875856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 411955868 (or 411955862 counting only the distinct ones).

The product of its digits is 423360000, while the sum is 69.

The spelling of 21375561875856 in words is "twenty-one trillion, three hundred seventy-five billion, five hundred sixty-one million, eight hundred seventy-five thousand, eight hundred fifty-six".