31131222121 has 4 divisors (see below), whose sum is σ = 31132184832. Its totient is φ = 31130259412.

The previous prime is 31131222079. The next prime is 31131222167. The reversal of 31131222121 is 12122213113.

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.

It is a cyclic number.

It is not a de Polignac number, because 31131222121 - 2²³ = 31122833513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31131222181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 431101 + ... + 498106.

It is an arithmetic number, because the mean of its divisors is an integer number (7783046208).

Almost surely, 2^31131222121 is an apocalyptic number.

It is an amenable number.

31131222121 is a deficient number, since it is larger than the sum of its proper divisors (962711).

31131222121 is an equidigital number, since it uses as much as digits as its factorization.

31131222121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 962710.

The product of its digits is 144, while the sum is 19.

Adding to 31131222121 its reverse (12122213113), we get a palindrome (43253435234).

The spelling of 31131222121 in words is "thirty-one billion, one hundred thirty-one million, two hundred twenty-two thousand, one hundred twenty-one".