31331987 has 2 divisors, whose sum is σ = 31331988. Its totient is φ = 31331986.

The previous prime is 31331959. The next prime is 31331999. The reversal of 31331987 is 78913313.

It is a strong prime.

It is an emirp because it is prime and its reverse (78913313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31331987 - 2¹⁰ = 31330963 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31331087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15665993 + 15665994.

It is an arithmetic number, because the mean of its divisors is an integer number (15665994).

Almost surely, 2^31331987 is an apocalyptic number.

31331987 is a deficient number, since it is larger than the sum of its proper divisors (1).

31331987 is an equidigital number, since it uses as much as digits as its factorization.

31331987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 35.

The square root of 31331987 is about 5597.4982804821. The cubic root of 31331987 is about 315.2554809865.

The spelling of 31331987 in words is "thirty-one million, three hundred thirty-one thousand, nine hundred eighty-seven".