15661372931 has 2 divisors, whose sum is σ = 15661372932. Its totient is φ = 15661372930.

The previous prime is 15661372901. The next prime is 15661372939. The reversal of 15661372931 is 13927316651.

It is a strong prime.

It is an emirp because it is prime and its reverse (13927316651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15661372931 - 2¹⁴ = 15661356547 is a prime.

It is a super-2 number, since 2×15661372931² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (15661372939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7830686465 + 7830686466.

It is an arithmetic number, because the mean of its divisors is an integer number (7830686466).

Almost surely, 2^15661372931 is an apocalyptic number.

15661372931 is a deficient number, since it is larger than the sum of its proper divisors (1).

15661372931 is an equidigital number, since it uses as much as digits as its factorization.

15661372931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204120, while the sum is 44.

The spelling of 15661372931 in words is "fifteen billion, six hundred sixty-one million, three hundred seventy-two thousand, nine hundred thirty-one".