31121223031021 has 2 divisors, whose sum is σ = 31121223031022. Its totient is φ = 31121223031020.

The previous prime is 31121223031009. The next prime is 31121223031061. The reversal of 31121223031021 is 12013032212113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26427197466121 + 4694025564900 = 5140739^2 + 2166570^2 .

It is an emirp because it is prime and its reverse (12013032212113) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31121223031021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31121223030983 and 31121223031001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31121223031061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15560611515510 + 15560611515511.

It is an arithmetic number, because the mean of its divisors is an integer number (15560611515511).

Almost surely, 2^{31121223031021} is an apocalyptic number.

It is an amenable number.

31121223031021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31121223031021 is an equidigital number, since it uses as much as digits as its factorization.

31121223031021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

Adding to 31121223031021 its reverse (12013032212113), we get a palindrome (43134255243134).

The spelling of 31121223031021 in words is "thirty-one trillion, one hundred twenty-one billion, two hundred twenty-three million, thirty-one thousand, twenty-one".