31717891 has 2 divisors, whose sum is σ = 31717892. Its totient is φ = 31717890.

The previous prime is 31717883. The next prime is 31717913. The reversal of 31717891 is 19871713.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31717891 - 2³ = 31717883 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31717891.

It is not a weakly prime, because it can be changed into another prime (31717811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15858945 + 15858946.

It is an arithmetic number, because the mean of its divisors is an integer number (15858946).

Almost surely, 2^31717891 is an apocalyptic number.

31717891 is a deficient number, since it is larger than the sum of its proper divisors (1).

31717891 is an equidigital number, since it uses as much as digits as its factorization.

31717891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10584, while the sum is 37.

The square root of 31717891 is about 5631.8639010544. The cubic root of 31717891 is about 316.5444966710.

The spelling of 31717891 in words is "thirty-one million, seven hundred seventeen thousand, eight hundred ninety-one".