31989161 has 2 divisors, whose sum is σ = 31989162. Its totient is φ = 31989160.

The previous prime is 31989137. The next prime is 31989163. The reversal of 31989161 is 16198913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18113536 + 13875625 = 4256^2 + 3725^2 .

It is a cyclic number.

It is not a de Polignac number, because 31989161 - 2¹⁰ = 31988137 is a prime.

It is a Sophie Germain prime.

Together with 31989163, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31989163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15994580 + 15994581.

It is an arithmetic number, because the mean of its divisors is an integer number (15994581).

Almost surely, 2^31989161 is an apocalyptic number.

It is an amenable number.

31989161 is a deficient number, since it is larger than the sum of its proper divisors (1).

31989161 is an equidigital number, since it uses as much as digits as its factorization.

31989161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 38.

The square root of 31989161 is about 5655.8961270518. The cubic root of 31989161 is about 317.4443608457. Note that the first 3 decimals are identical.

The spelling of 31989161 in words is "thirty-one million, nine hundred eighty-nine thousand, one hundred sixty-one".