31691357393 has 4 divisors (see below), whose sum is σ = 31759219440. Its totient is φ = 31623495348.

The previous prime is 31691357377. The next prime is 31691357419. The reversal of 31691357393 is 39375319613.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39375319613 = 7 ⋅5625045659.

It is a cyclic number.

It is not a de Polignac number, because 31691357393 - 2⁴ = 31691357377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31691347393) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33930323 + ... + 33931256.

It is an arithmetic number, because the mean of its divisors is an integer number (7939804860).

Almost surely, 2^31691357393 is an apocalyptic number.

It is an amenable number.

31691357393 is a deficient number, since it is larger than the sum of its proper divisors (67862047).

31691357393 is an equidigital number, since it uses as much as digits as its factorization.

31691357393 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67862046.

The product of its digits is 1377810, while the sum is 50.

The spelling of 31691357393 in words is "thirty-one billion, six hundred ninety-one million, three hundred fifty-seven thousand, three hundred ninety-three".