31131987 has 4 divisors (see below), whose sum is σ = 41509320. Its totient is φ = 20754656.

The previous prime is 31131979. The next prime is 31132027. The reversal of 31131987 is 78913113.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31131987 - 2³ = 31131979 is a prime.

It is a super-2 number, since 2×31131987² = 1938401229136338, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (31131977) 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 in 3 ways as a sum of consecutive naturals, for example, 5188662 + ... + 5188667.

It is an arithmetic number, because the mean of its divisors is an integer number (10377330).

Almost surely, 2^31131987 is an apocalyptic number.

31131987 is a deficient number, since it is larger than the sum of its proper divisors (10377333).

31131987 is a wasteful number, since it uses less digits than its factorization.

31131987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10377332.

The product of its digits is 4536, while the sum is 33.

The square root of 31131987 is about 5579.6045558803. The cubic root of 31131987 is about 314.5832634748.

The spelling of 31131987 in words is "thirty-one million, one hundred thirty-one thousand, nine hundred eighty-seven".