31311013021 has 2 divisors, whose sum is σ = 31311013022. Its totient is φ = 31311013020.

The previous prime is 31311012983. The next prime is 31311013031. The reversal of 31311013021 is 12031011313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26722440900 + 4588572121 = 163470^2 + 67739^2 .

It is an emirp because it is prime and its reverse (12031011313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31311013021 - 2¹⁷ = 31310881949 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31311012986 and 31311013004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31311013031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15655506510 + 15655506511.

It is an arithmetic number, because the mean of its divisors is an integer number (15655506511).

Almost surely, 2^31311013021 is an apocalyptic number.

It is an amenable number.

31311013021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31311013021 is an equidigital number, since it uses as much as digits as its factorization.

31311013021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54, while the sum is 16.

Adding to 31311013021 its reverse (12031011313), we get a palindrome (43342024334).

The spelling of 31311013021 in words is "thirty-one billion, three hundred eleven million, thirteen thousand, twenty-one".