21715264321 has 27 divisors (see below), whose sum is σ = 23397674979. Its totient is φ = 20151911472.

The previous prime is 21715264301. The next prime is 21715264343. The reversal of 21715264321 is 12346251712.

The square root of 21715264321 is 147361.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 2544092721 + 19171171600 = 50439^2 + 138460^2 .

It is not a de Polignac number, because 21715264321 - 2⁵ = 21715264289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715264301) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 145739955 + ... + 145740103.

Almost surely, 2^21715264321 is an apocalyptic number.

21715264321 is the 147361-st square number.

21715264321 is the 73681-st centered octagonal number.

It is an amenable number.

21715264321 is a deficient number, since it is larger than the sum of its proper divisors (1682410658).

21715264321 is an frugal number, since it uses more digits than its factorization.

21715264321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430 (or 215 counting only the distinct ones).

The product of its digits is 20160, while the sum is 34.

The spelling of 21715264321 in words is "twenty-one billion, seven hundred fifteen million, two hundred sixty-four thousand, three hundred twenty-one".