31913918 has 4 divisors (see below), whose sum is σ = 47870880. Its totient is φ = 15956958.

The previous prime is 31913839. The next prime is 31913923. The reversal of 31913918 is 81931913.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81931913 = 7 ⋅11704559.

It is a super-2 number, since 2×31913918² = 2036996324221448, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7978478 + ... + 7978481.

It is an arithmetic number, because the mean of its divisors is an integer number (11967720).

Almost surely, 2^31913918 is an apocalyptic number.

31913918 is a deficient number, since it is larger than the sum of its proper divisors (15956962).

31913918 is a wasteful number, since it uses less digits than its factorization.

31913918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15956961.

The product of its digits is 5832, while the sum is 35.

The square root of 31913918 is about 5649.2404799229. The cubic root of 31913918 is about 317.1952742058.

The spelling of 31913918 in words is "thirty-one million, nine hundred thirteen thousand, nine hundred eighteen".