31868981 has 4 divisors (see below), whose sum is σ = 32047200. Its totient is φ = 31690764.

The previous prime is 31868939. The next prime is 31868983. The reversal of 31868981 is 18986813.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18986813 = 41 ⋅463093.

It is a cyclic number.

It is not a de Polignac number, because 31868981 - 2⁶ = 31868917 is a prime.

It is a super-2 number, since 2×31868981² = 2031263899956722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31868983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 88841 + ... + 89198.

It is an arithmetic number, because the mean of its divisors is an integer number (8011800).

Almost surely, 2^31868981 is an apocalyptic number.

It is an amenable number.

31868981 is a deficient number, since it is larger than the sum of its proper divisors (178219).

31868981 is a wasteful number, since it uses less digits than its factorization.

31868981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178218.

The product of its digits is 82944, while the sum is 44.

The square root of 31868981 is about 5645.2618185519. The cubic root of 31868981 is about 317.0463266590.

It can be divided in two parts, 3186 and 8981, that added together give a cube (12167 = 23³).

The spelling of 31868981 in words is "thirty-one million, eight hundred sixty-eight thousand, nine hundred eighty-one".