31155989 has 2 divisors, whose sum is σ = 31155990. Its totient is φ = 31155988.

The previous prime is 31155979. The next prime is 31156001. The reversal of 31155989 is 98955113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30713764 + 442225 = 5542^2 + 665^2 .

It is a cyclic number.

It is not a de Polignac number, because 31155989 - 2⁴ = 31155973 is a prime.

It is a Sophie Germain prime.

It is a Chen 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 (31155979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15577994 + 15577995.

It is an arithmetic number, because the mean of its divisors is an integer number (15577995).

Almost surely, 2^31155989 is an apocalyptic number.

It is an amenable number.

31155989 is a deficient number, since it is larger than the sum of its proper divisors (1).

31155989 is an equidigital number, since it uses as much as digits as its factorization.

31155989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48600, while the sum is 41.

The square root of 31155989 is about 5581.7550107471. The cubic root of 31155989 is about 314.6640880393.

The spelling of 31155989 in words is "thirty-one million, one hundred fifty-five thousand, nine hundred eighty-nine".