31517392891 has 2 divisors, whose sum is σ = 31517392892. Its totient is φ = 31517392890.

The previous prime is 31517392861. The next prime is 31517392897. The reversal of 31517392891 is 19829371513.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31517392891 is a prime.

It is not a weakly prime, because it can be changed into another prime (31517392897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15758696445 + 15758696446.

It is an arithmetic number, because the mean of its divisors is an integer number (15758696446).

Almost surely, 2^31517392891 is an apocalyptic number.

31517392891 is a deficient number, since it is larger than the sum of its proper divisors (1).

31517392891 is an equidigital number, since it uses as much as digits as its factorization.

31517392891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 408240, while the sum is 49.

The spelling of 31517392891 in words is "thirty-one billion, five hundred seventeen million, three hundred ninety-two thousand, eight hundred ninety-one".