21564888378 has 24 divisors (see below), whose sum is σ = 47407111584. Its totient is φ = 6534814440.

The previous prime is 21564888361. The next prime is 21564888383. The reversal of 21564888378 is 87388846512.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14851126 + ... + 14852577.

It is an arithmetic number, because the mean of its divisors is an integer number (1975296316).

Almost surely, 2^21564888378 is an apocalyptic number.

21564888378 is an abundant number, since it is smaller than the sum of its proper divisors (25842223206).

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

21564888378 is a wasteful number, since it uses less digits than its factorization.

21564888378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29703730 (or 29703719 counting only the distinct ones).

The product of its digits is 20643840, while the sum is 60.

The spelling of 21564888378 in words is "twenty-one billion, five hundred sixty-four million, eight hundred eighty-eight thousand, three hundred seventy-eight".