21715844913 has 12 divisors (see below), whose sum is σ = 35848379008. Its totient is φ = 12409054200.

The previous prime is 21715844903. The next prime is 21715844923. The reversal of 21715844913 is 31944851712.

21715844913 is a `hidden beast` number, since 2 + 1 + 7 + 158 + 4 + 491 + 3 = 666.

It is an interprime number because it is at equal distance from previous prime (21715844903) and next prime (21715844923).

It is not a de Polignac number, because 21715844913 - 2⁵ = 21715844881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715844903) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 172347913 + ... + 172348038.

Almost surely, 2^21715844913 is an apocalyptic number.

It is an amenable number.

21715844913 is a deficient number, since it is larger than the sum of its proper divisors (14132534095).

21715844913 is a wasteful number, since it uses less digits than its factorization.

21715844913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344695964 (or 344695961 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The spelling of 21715844913 in words is "twenty-one billion, seven hundred fifteen million, eight hundred forty-four thousand, nine hundred thirteen".