31987690 has 48 divisors (see below), whose sum is σ = 67769352. Its totient is φ = 10838016.

The previous prime is 31987663. The next prime is 31987699. The reversal of 31987690 is 9678913.

It can be written as a sum of positive squares in 4 ways, for example, as 22458121 + 9529569 = 4739^2 + 3087^2 .

It is a super-2 number, since 2×31987690² = 2046424623072200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (31987699) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 47194 + ... + 47866.

Almost surely, 2^31987690 is an apocalyptic number.

31987690 is an abundant number, since it is smaller than the sum of its proper divisors (35781662).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31987690 is a wasteful number, since it uses less digits than its factorization.

31987690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 791 (or 784 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 43.

The square root of 31987690 is about 5655.7660842719. The cubic root of 31987690 is about 317.4394949495.

The spelling of 31987690 in words is "thirty-one million, nine hundred eighty-seven thousand, six hundred ninety".