21578806716 has 24 divisors (see below), whose sum is σ = 51040284624. Its totient is φ = 7094401920.

The previous prime is 21578806699. The next prime is 21578806727. The reversal of 21578806716 is 61760887512.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12315795 + ... + 12317546.

It is an arithmetic number, because the mean of its divisors is an integer number (2126678526).

Almost surely, 2^21578806716 is an apocalyptic number.

It is an amenable number.

21578806716 is an abundant number, since it is smaller than the sum of its proper divisors (29461477908).

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

21578806716 is a wasteful number, since it uses less digits than its factorization.

21578806716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24633421 (or 24633419 counting only the distinct ones).

The product of its (nonzero) digits is 1128960, while the sum is 51.

The spelling of 21578806716 in words is "twenty-one billion, five hundred seventy-eight million, eight hundred six thousand, seven hundred sixteen".