31987681 has 12 divisors (see below), whose sum is σ = 35392896. Its totient is φ = 28887320.

The previous prime is 31987663. The next prime is 31987699. The reversal of 31987681 is 18678913.

It is an interprime number because it is at equal distance from previous prime (31987663) and next prime (31987699).

It is not a de Polignac number, because 31987681 - 2¹¹ = 31985633 is a prime.

It is a super-2 number, since 2×31987681² = 2046423471515522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (31987601) 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 11 ways as a sum of consecutive naturals, for example, 19416 + ... + 20998.

It is an arithmetic number, because the mean of its divisors is an integer number (2949408).

Almost surely, 2^31987681 is an apocalyptic number.

It is an amenable number.

31987681 is a deficient number, since it is larger than the sum of its proper divisors (3405215).

31987681 is a wasteful number, since it uses less digits than its factorization.

31987681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1772 (or 1761 counting only the distinct ones).

The product of its digits is 72576, while the sum is 43.

The square root of 31987681 is about 5655.7652886236. The cubic root of 31987681 is about 317.4394651781.

The spelling of 31987681 in words is "thirty-one million, nine hundred eighty-seven thousand, six hundred eighty-one".