31631112721 has 4 divisors (see below), whose sum is σ = 34064275252. Its totient is φ = 29197950192.

The previous prime is 31631112701. The next prime is 31631112727. The reversal of 31631112721 is 12721113613.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12721113613 = 13 ⋅978547201.

It can be written as a sum of positive squares in 2 ways, for example, as 21703182400 + 9927930321 = 147320^2 + 99639^2 .

It is a cyclic number.

It is not a de Polignac number, because 31631112721 - 2⁷ = 31631112593 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31631112721.

It is not an unprimeable number, because it can be changed into a prime (31631112727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1216581246 + ... + 1216581271.

It is an arithmetic number, because the mean of its divisors is an integer number (8516068813).

Almost surely, 2^31631112721 is an apocalyptic number.

It is an amenable number.

31631112721 is a deficient number, since it is larger than the sum of its proper divisors (2433162531).

31631112721 is a wasteful number, since it uses less digits than its factorization.

31631112721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2433162530.

The product of its digits is 1512, while the sum is 28.

The spelling of 31631112721 in words is "thirty-one billion, six hundred thirty-one million, one hundred twelve thousand, seven hundred twenty-one".