31313441221 has 2 divisors, whose sum is σ = 31313441222. Its totient is φ = 31313441220.

The previous prime is 31313441213. The next prime is 31313441231. The reversal of 31313441221 is 12214431313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30805164196 + 508277025 = 175514^2 + 22545^2 .

It is a cyclic number.

It is not a de Polignac number, because 31313441221 - 2³ = 31313441213 is a prime.

It is a super-2 number, since 2×31313441221² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31313441231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15656720610 + 15656720611.

It is an arithmetic number, because the mean of its divisors is an integer number (15656720611).

Almost surely, 2^31313441221 is an apocalyptic number.

It is an amenable number.

31313441221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31313441221 is an equidigital number, since it uses as much as digits as its factorization.

31313441221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 25.

Adding to 31313441221 its reverse (12214431313), we get a palindrome (43527872534).

The spelling of 31313441221 in words is "thirty-one billion, three hundred thirteen million, four hundred forty-one thousand, two hundred twenty-one".