31631989 has 2 divisors, whose sum is σ = 31631990. Its totient is φ = 31631988.

The previous prime is 31631981. The next prime is 31631993. The reversal of 31631989 is 98913613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26936100 + 4695889 = 5190^2 + 2167^2 .

It is a cyclic number.

It is not a de Polignac number, because 31631989 - 2³ = 31631981 is a prime.

It is a super-2 number, since 2×31631989² = 2001165456192242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31631981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15815994 + 15815995.

It is an arithmetic number, because the mean of its divisors is an integer number (15815995).

Almost surely, 2^31631989 is an apocalyptic number.

It is an amenable number.

31631989 is a deficient number, since it is larger than the sum of its proper divisors (1).

31631989 is an equidigital number, since it uses as much as digits as its factorization.

31631989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 40.

The square root of 31631989 is about 5624.2323031681. The cubic root of 31631989 is about 316.2584710297.

The spelling of 31631989 in words is "thirty-one million, six hundred thirty-one thousand, nine hundred eighty-nine".