31311203221 has 2 divisors, whose sum is σ = 31311203222. Its totient is φ = 31311203220.

The previous prime is 31311203179. The next prime is 31311203267. The reversal of 31311203221 is 12230211313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18683062596 + 12628140625 = 136686^2 + 112375^2 .

It is an emirp because it is prime and its reverse (12230211313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31311203221 - 2²⁵ = 31277648789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31311203291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15655601610 + 15655601611.

It is an arithmetic number, because the mean of its divisors is an integer number (15655601611).

Almost surely, 2^31311203221 is an apocalyptic number.

It is an amenable number.

31311203221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31311203221 is an equidigital number, since it uses as much as digits as its factorization.

31311203221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 31311203221 its reverse (12230211313), we get a palindrome (43541414534).

The spelling of 31311203221 in words is "thirty-one billion, three hundred eleven million, two hundred three thousand, two hundred twenty-one".