21315350644 has 18 divisors (see below), whose sum is σ = 43391964210. Its totient is φ = 9135150192.

The previous prime is 21315350629. The next prime is 21315350657. The reversal of 21315350644 is 44605351312.

It can be written as a sum of positive squares in only one way, i.e., 13610022244 + 7705328400 = 116662^2 + 87780^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 54375699 + ... + 54376090.

Almost surely, 2^21315350644 is an apocalyptic number.

It is an amenable number.

21315350644 is an abundant number, since it is smaller than the sum of its proper divisors (22076613566).

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

21315350644 is a wasteful number, since it uses less digits than its factorization.

21315350644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108751807 (or 108751798 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

The spelling of 21315350644 in words is "twenty-one billion, three hundred fifteen million, three hundred fifty thousand, six hundred forty-four".