31123221989 has 2 divisors, whose sum is σ = 31123221990. Its totient is φ = 31123221988.

The previous prime is 31123221973. The next prime is 31123222019. The reversal of 31123221989 is 98912232113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30586512100 + 536709889 = 174890^2 + 23167^2 .

It is a cyclic number.

It is not a de Polignac number, because 31123221989 - 2⁴ = 31123221973 is a prime.

It is a super-2 number, since 2×31123221989² (a number of 22 digits) contains 22 as substring.

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 (31123221919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15561610994 + 15561610995.

It is an arithmetic number, because the mean of its divisors is an integer number (15561610995).

Almost surely, 2^31123221989 is an apocalyptic number.

It is an amenable number.

31123221989 is a deficient number, since it is larger than the sum of its proper divisors (1).

31123221989 is an equidigital number, since it uses as much as digits as its factorization.

31123221989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 41.

The spelling of 31123221989 in words is "thirty-one billion, one hundred twenty-three million, two hundred twenty-one thousand, nine hundred eighty-nine".