31887661 has 4 divisors (see below), whose sum is σ = 34340572. Its totient is φ = 29434752.

The previous prime is 31887649. The next prime is 31887679. The reversal of 31887661 is 16678813.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16678813 = 997 ⋅16729.

It can be written as a sum of positive squares in 2 ways, for example, as 14822500 + 17065161 = 3850^2 + 4131^2 .

It is a cyclic number.

It is not a de Polignac number, because 31887661 - 2⁵ = 31887629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31887061) 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, 1226436 + ... + 1226461.

It is an arithmetic number, because the mean of its divisors is an integer number (8585143).

Almost surely, 2^31887661 is an apocalyptic number.

It is an amenable number.

31887661 is a deficient number, since it is larger than the sum of its proper divisors (2452911).

31887661 is a wasteful number, since it uses less digits than its factorization.

31887661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2452910.

The product of its digits is 48384, while the sum is 40.

The square root of 31887661 is about 5646.9160610018. The cubic root of 31887661 is about 317.1082601173.

The spelling of 31887661 in words is "thirty-one million, eight hundred eighty-seven thousand, six hundred sixty-one".