31213023221 has 2 divisors, whose sum is σ = 31213023222. Its totient is φ = 31213023220.

The previous prime is 31213023203. The next prime is 31213023229. The reversal of 31213023221 is 12232031213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28733979121 + 2479044100 = 169511^2 + 49790^2 .

It is a cyclic number.

It is not a de Polignac number, because 31213023221 - 2⁶ = 31213023157 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31213023193 and 31213023202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31213023229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15606511610 + 15606511611.

It is an arithmetic number, because the mean of its divisors is an integer number (15606511611).

Almost surely, 2^31213023221 is an apocalyptic number.

It is an amenable number.

31213023221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31213023221 is an equidigital number, since it uses as much as digits as its factorization.

31213023221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 31213023221 its reverse (12232031213), we get a palindrome (43445054434).

The spelling of 31213023221 in words is "thirty-one billion, two hundred thirteen million, twenty-three thousand, two hundred twenty-one".