31390987 has 2 divisors, whose sum is σ = 31390988. Its totient is φ = 31390986.

The previous prime is 31390979. The next prime is 31391033. The reversal of 31390987 is 78909313.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31390987 - 2³ = 31390979 is a prime.

It is not a weakly prime, because it can be changed into another prime (31390927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15695493 + 15695494.

It is an arithmetic number, because the mean of its divisors is an integer number (15695494).

Almost surely, 2^31390987 is an apocalyptic number.

31390987 is a deficient number, since it is larger than the sum of its proper divisors (1).

31390987 is an equidigital number, since it uses as much as digits as its factorization.

31390987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 31390987 is about 5602.7660133188. The cubic root of 31390987 is about 315.4532385323.

The spelling of 31390987 in words is "thirty-one million, three hundred ninety thousand, nine hundred eighty-seven".