31213133221 has 2 divisors, whose sum is σ = 31213133222. Its totient is φ = 31213133220.

The previous prime is 31213133209. The next prime is 31213133233. The reversal of 31213133221 is 12233131213.

It is a balanced prime because it is at equal distance from previous prime (31213133209) and next prime (31213133233).

It can be written as a sum of positive squares in only one way, i.e., 27444892225 + 3768240996 = 165665^2 + 61386^2 .

It is a cyclic number.

It is not a de Polignac number, because 31213133221 - 2³¹ = 29065649573 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31213133192 and 31213133201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31213133261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15606566610 + 15606566611.

It is an arithmetic number, because the mean of its divisors is an integer number (15606566611).

Almost surely, 2^31213133221 is an apocalyptic number.

It is an amenable number.

31213133221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31213133221 is an equidigital number, since it uses as much as digits as its factorization.

31213133221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 22.

Adding to 31213133221 its reverse (12233131213), we get a palindrome (43446264434).

The spelling of 31213133221 in words is "thirty-one billion, two hundred thirteen million, one hundred thirty-three thousand, two hundred twenty-one".