31258991 has 2 divisors, whose sum is σ = 31258992. Its totient is φ = 31258990.

The previous prime is 31258987. The next prime is 31258993. The reversal of 31258991 is 19985213.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31258991 - 2² = 31258987 is a prime.

Together with 31258993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31258993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15629495 + 15629496.

It is an arithmetic number, because the mean of its divisors is an integer number (15629496).

Almost surely, 2^31258991 is an apocalyptic number.

31258991 is a deficient number, since it is larger than the sum of its proper divisors (1).

31258991 is an equidigital number, since it uses as much as digits as its factorization.

31258991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 38.

The square root of 31258991 is about 5590.9740654022. The cubic root of 31258991 is about 315.0104674442.

The spelling of 31258991 in words is "thirty-one million, two hundred fifty-eight thousand, nine hundred ninety-one".