21308814636 has 12 divisors (see below), whose sum is σ = 49720567512. Its totient is φ = 7102938208.

The previous prime is 21308814629. The next prime is 21308814643. The reversal of 21308814636 is 63641880312.

It is an interprime number because it is at equal distance from previous prime (21308814629) and next prime (21308814643).

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 887867265 + ... + 887867288.

It is an arithmetic number, because the mean of its divisors is an integer number (4143380626).

Almost surely, 2^21308814636 is an apocalyptic number.

It is an amenable number.

21308814636 is an abundant number, since it is smaller than the sum of its proper divisors (28411752876).

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

21308814636 is a wasteful number, since it uses less digits than its factorization.

21308814636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1775734560 (or 1775734558 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 42.

The spelling of 21308814636 in words is "twenty-one billion, three hundred eight million, eight hundred fourteen thousand, six hundred thirty-six".