21715307731 has 16 divisors (see below), whose sum is σ = 24793007904. Its totient is φ = 18841665024.

The previous prime is 21715307723. The next prime is 21715307749. The reversal of 21715307731 is 13770351712.

It is not a de Polignac number, because 21715307731 - 2³ = 21715307723 is a prime.

It is a super-2 number, since 2×21715307731² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715307771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111501 + ... + 236353.

It is an arithmetic number, because the mean of its divisors is an integer number (1549562994).

Almost surely, 2^21715307731 is an apocalyptic number.

21715307731 is a deficient number, since it is larger than the sum of its proper divisors (3077700173).

21715307731 is a wasteful number, since it uses less digits than its factorization.

21715307731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125670.

The product of its (nonzero) digits is 30870, while the sum is 37.

The spelling of 21715307731 in words is "twenty-one billion, seven hundred fifteen million, three hundred seven thousand, seven hundred thirty-one".