31987117 has 2 divisors, whose sum is σ = 31987118. Its totient is φ = 31987116.

The previous prime is 31987099. The next prime is 31987139. The reversal of 31987117 is 71178913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31651876 + 335241 = 5626^2 + 579^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31987117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31987147) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15993558 + 15993559.

It is an arithmetic number, because the mean of its divisors is an integer number (15993559).

Almost surely, 2^31987117 is an apocalyptic number.

It is an amenable number.

31987117 is a deficient number, since it is larger than the sum of its proper divisors (1).

31987117 is an equidigital number, since it uses as much as digits as its factorization.

31987117 is an odious number, because the sum of its binary digits is odd.

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

The square root of 31987117 is about 5655.7154277775. The cubic root of 31987117 is about 317.4375994920.

The spelling of 31987117 in words is "thirty-one million, nine hundred eighty-seven thousand, one hundred seventeen".