31918 has 4 divisors (see below), whose sum is σ = 47880. Its totient is φ = 15958.

The previous prime is 31907. The next prime is 31957. The reversal of 31918 is 81913.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81913 = 13 ⋅6301.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7978 + ... + 7981.

It is an arithmetic number, because the mean of its divisors is an integer number (11970).

2³¹⁹¹⁸ is an apocalyptic number.

31918 is a deficient number, since it is larger than the sum of its proper divisors (15962).

31918 is a wasteful number, since it uses less digits than its factorization.

31918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15961.

The product of its digits is 216, while the sum is 22.

The square root of 31918 is about 178.6560942146. The cubic root of 31918 is about 31.7208797416.

It can be divided in two parts, 31 and 918, that added together give a palindrome (949).

The spelling of 31918 in words is "thirty-one thousand, nine hundred eighteen".