31991293 has 2 divisors, whose sum is σ = 31991294. Its totient is φ = 31991292.

The previous prime is 31991249. The next prime is 31991299. The reversal of 31991293 is 39219913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18130564 + 13860729 = 4258^2 + 3723^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31991293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31991299) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995646 + 15995647.

It is an arithmetic number, because the mean of its divisors is an integer number (15995647).

Almost surely, 2^31991293 is an apocalyptic number.

It is an amenable number.

31991293 is a deficient number, since it is larger than the sum of its proper divisors (1).

31991293 is an equidigital number, since it uses as much as digits as its factorization.

31991293 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13122, while the sum is 37.

The square root of 31991293 is about 5656.0845997916. The cubic root of 31991293 is about 317.4514129880.

The spelling of 31991293 in words is "thirty-one million, nine hundred ninety-one thousand, two hundred ninety-three".