31231111321 has 4 divisors (see below), whose sum is σ = 31232267572. Its totient is φ = 31229955072.

The previous prime is 31231111273. The next prime is 31231111363. The reversal of 31231111321 is 12311113213.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1635070096 + 29596041225 = 40436^2 + 172035^2 .

It is a cyclic number.

It is not a de Polignac number, because 31231111321 - 2¹⁵ = 31231078553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31231151321) 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, 536616 + ... + 591961.

It is an arithmetic number, because the mean of its divisors is an integer number (7808066893).

Almost surely, 2^31231111321 is an apocalyptic number.

It is an amenable number.

31231111321 is a deficient number, since it is larger than the sum of its proper divisors (1156251).

31231111321 is a wasteful number, since it uses less digits than its factorization.

31231111321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156250.

The product of its digits is 108, while the sum is 19.

Adding to 31231111321 its reverse (12311113213), we get a palindrome (43542224534).

It can be divided in two parts, 3 and 1231111321, that multiplied together give a palindrome (3693333963).

The spelling of 31231111321 in words is "thirty-one billion, two hundred thirty-one million, one hundred eleven thousand, three hundred twenty-one".