31139287 has 2 divisors, whose sum is σ = 31139288. Its totient is φ = 31139286.

The previous prime is 31139279. The next prime is 31139299. The reversal of 31139287 is 78293113.

It is a weak prime.

It is an emirp because it is prime and its reverse (78293113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31139287 - 2³ = 31139279 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31139687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15569643 + 15569644.

It is an arithmetic number, because the mean of its divisors is an integer number (15569644).

Almost surely, 2^31139287 is an apocalyptic number.

31139287 is a deficient number, since it is larger than the sum of its proper divisors (1).

31139287 is an equidigital number, since it uses as much as digits as its factorization.

31139287 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 34.

The square root of 31139287 is about 5580.2586857600. The cubic root of 31139287 is about 314.6078499593.

The spelling of 31139287 in words is "thirty-one million, one hundred thirty-nine thousand, two hundred eighty-seven".