31991249 has 2 divisors, whose sum is σ = 31991250. Its totient is φ = 31991248.

The previous prime is 31991237. The next prime is 31991293. The reversal of 31991249 is 94219913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29235649 + 2755600 = 5407^2 + 1660^2 .

It is a cyclic number.

It is not a de Polignac number, because 31991249 - 2⁴ = 31991233 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31991209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995624 + 15995625.

It is an arithmetic number, because the mean of its divisors is an integer number (15995625).

Almost surely, 2^31991249 is an apocalyptic number.

It is an amenable number.

31991249 is a deficient number, since it is larger than the sum of its proper divisors (1).

31991249 is an equidigital number, since it uses as much as digits as its factorization.

31991249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 38.

The square root of 31991249 is about 5656.0807101738. The cubic root of 31991249 is about 317.4512674497.

The spelling of 31991249 in words is "thirty-one million, nine hundred ninety-one thousand, two hundred forty-nine".