31887139 has 2 divisors, whose sum is σ = 31887140. Its totient is φ = 31887138.

The previous prime is 31887137. The next prime is 31887143. The reversal of 31887139 is 93178813.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31887139 - 2¹ = 31887137 is a prime.

Together with 31887137, it forms a pair of twin primes.

It is equal to p_1967296 and since 31887139 and 1967296 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (31887137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15943569 + 15943570.

It is an arithmetic number, because the mean of its divisors is an integer number (15943570).

Almost surely, 2^31887139 is an apocalyptic number.

31887139 is a deficient number, since it is larger than the sum of its proper divisors (1).

31887139 is an equidigital number, since it uses as much as digits as its factorization.

31887139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 40.

The square root of 31887139 is about 5646.8698408942. The cubic root of 31887139 is about 317.1065297571.

The spelling of 31887139 in words is "thirty-one million, eight hundred eighty-seven thousand, one hundred thirty-nine".