31709987 has 2 divisors, whose sum is σ = 31709988. Its totient is φ = 31709986.

The previous prime is 31709941. The next prime is 31710023. The reversal of 31709987 is 78990713.

It is a strong prime.

It is an emirp because it is prime and its reverse (78990713) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31709987 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31709927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15854993 + 15854994.

It is an arithmetic number, because the mean of its divisors is an integer number (15854994).

Almost surely, 2^31709987 is an apocalyptic number.

31709987 is a deficient number, since it is larger than the sum of its proper divisors (1).

31709987 is an equidigital number, since it uses as much as digits as its factorization.

31709987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 95256, while the sum is 44.

The square root of 31709987 is about 5631.1621358295. The cubic root of 31709987 is about 316.5182005178.

The spelling of 31709987 in words is "thirty-one million, seven hundred nine thousand, nine hundred eighty-seven".