31991257289 has 2 divisors, whose sum is σ = 31991257290. Its totient is φ = 31991257288.

The previous prime is 31991257279. The next prime is 31991257367. The reversal of 31991257289 is 98275219913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19920499600 + 12070757689 = 141140^2 + 109867^2 .

It is a cyclic number.

It is not a de Polignac number, because 31991257289 - 2¹² = 31991253193 is a prime.

It is not a weakly prime, because it can be changed into another prime (31991257219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995628644 + 15995628645.

It is an arithmetic number, because the mean of its divisors is an integer number (15995628645).

Almost surely, 2^31991257289 is an apocalyptic number.

It is an amenable number.

31991257289 is a deficient number, since it is larger than the sum of its proper divisors (1).

31991257289 is an equidigital number, since it uses as much as digits as its factorization.

31991257289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2449440, while the sum is 56.

The spelling of 31991257289 in words is "thirty-one billion, nine hundred ninety-one million, two hundred fifty-seven thousand, two hundred eighty-nine".