31313220217 has 2 divisors, whose sum is σ = 31313220218. Its totient is φ = 31313220216.

The previous prime is 31313220209. The next prime is 31313220251. The reversal of 31313220217 is 71202231313.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23493532176 + 7819688041 = 153276^2 + 88429^2 .

It is an emirp because it is prime and its reverse (71202231313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31313220217 - 2³ = 31313220209 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31313220191 and 31313220200.

It is not a weakly prime, because it can be changed into another prime (31313227217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15656610108 + 15656610109.

It is an arithmetic number, because the mean of its divisors is an integer number (15656610109).

Almost surely, 2^31313220217 is an apocalyptic number.

It is an amenable number.

31313220217 is a deficient number, since it is larger than the sum of its proper divisors (1).

31313220217 is an equidigital number, since it uses as much as digits as its factorization.

31313220217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512, while the sum is 25.

The spelling of 31313220217 in words is "thirty-one billion, three hundred thirteen million, two hundred twenty thousand, two hundred seventeen".