21909379508 has 6 divisors (see below), whose sum is σ = 38341414146. Its totient is φ = 10954689752.

The previous prime is 21909379501. The next prime is 21909379511. The reversal of 21909379508 is 80597390912.

It can be written as a sum of positive squares in only one way, i.e., 12956813584 + 8952565924 = 113828^2 + 94618^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21909379508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909379501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2738672435 + ... + 2738672442.

It is an arithmetic number, because the mean of its divisors is an integer number (6390235691).

Almost surely, 2^21909379508 is an apocalyptic number.

It is an amenable number.

21909379508 is a deficient number, since it is larger than the sum of its proper divisors (16432034638).

21909379508 is a wasteful number, since it uses less digits than its factorization.

21909379508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5477344881 (or 5477344879 counting only the distinct ones).

The product of its (nonzero) digits is 1224720, while the sum is 53.

The spelling of 21909379508 in words is "twenty-one billion, nine hundred nine million, three hundred seventy-nine thousand, five hundred eight".