31312221173 has 2 divisors, whose sum is σ = 31312221174. Its totient is φ = 31312221172.

The previous prime is 31312221169. The next prime is 31312221319. The reversal of 31312221173 is 37112221313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30589310404 + 722910769 = 174898^2 + 26887^2 .

It is a cyclic number.

It is not a de Polignac number, because 31312221173 - 2² = 31312221169 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31312227173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15656110586 + 15656110587.

It is an arithmetic number, because the mean of its divisors is an integer number (15656110587).

Almost surely, 2^31312221173 is an apocalyptic number.

It is an amenable number.

31312221173 is a deficient number, since it is larger than the sum of its proper divisors (1).

31312221173 is an equidigital number, since it uses as much as digits as its factorization.

31312221173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1512, while the sum is 26.

Adding to 31312221173 its reverse (37112221313), we get a palindrome (68424442486).

The spelling of 31312221173 in words is "thirty-one billion, three hundred twelve million, two hundred twenty-one thousand, one hundred seventy-three".