31312031021 has 2 divisors, whose sum is σ = 31312031022. Its totient is φ = 31312031020.

The previous prime is 31312030999. The next prime is 31312031123. The reversal of 31312031021 is 12013021313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20566428100 + 10745602921 = 143410^2 + 103661^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31312031021 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31312031221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15656015510 + 15656015511.

It is an arithmetic number, because the mean of its divisors is an integer number (15656015511).

Almost surely, 2^31312031021 is an apocalyptic number.

It is an amenable number.

31312031021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31312031021 is an equidigital number, since it uses as much as digits as its factorization.

31312031021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 17.

Adding to 31312031021 its reverse (12013021313), we get a palindrome (43325052334).

The spelling of 31312031021 in words is "thirty-one billion, three hundred twelve million, thirty-one thousand, twenty-one".