31231131021 has 12 divisors (see below), whose sum is σ = 45655148448. Its totient is φ = 20569901064.

The previous prime is 31231131013. The next prime is 31231131073. The reversal of 31231131021 is 12013113213.

It is not a de Polignac number, because 31231131021 - 2³ = 31231131013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31231130985 and 31231131003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31231131121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20903625 + ... + 20905118.

It is an arithmetic number, because the mean of its divisors is an integer number (3804595704).

Almost surely, 2^31231131021 is an apocalyptic number.

It is an amenable number.

31231131021 is a deficient number, since it is larger than the sum of its proper divisors (14424017427).

31231131021 is a wasteful number, since it uses less digits than its factorization.

31231131021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41808832 (or 41808829 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

Adding to 31231131021 its reverse (12013113213), we get a palindrome (43244244234).

The spelling of 31231131021 in words is "thirty-one billion, two hundred thirty-one million, one hundred thirty-one thousand, twenty-one".