21771438924 has 12 divisors (see below), whose sum is σ = 50800024184. Its totient is φ = 7257146304.

The previous prime is 21771438863. The next prime is 21771438947. The reversal of 21771438924 is 42983417712.

It is a tau number, because it is divible by the number of its divisors (12).

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 3 ways as a sum of consecutive naturals, for example, 907143277 + ... + 907143300.

Almost surely, 2^21771438924 is an apocalyptic number.

It is an amenable number.

21771438924 is an abundant number, since it is smaller than the sum of its proper divisors (29028585260).

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

21771438924 is a wasteful number, since it uses less digits than its factorization.

21771438924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1814286584 (or 1814286582 counting only the distinct ones).

The product of its digits is 677376, while the sum is 48.

The spelling of 21771438924 in words is "twenty-one billion, seven hundred seventy-one million, four hundred thirty-eight thousand, nine hundred twenty-four".