31686945 has 16 divisors (see below), whose sum is σ = 51414912. Its totient is φ = 16661120.

The previous prime is 31686931. The next prime is 31686947. The reversal of 31686945 is 54968613.

It is not a de Polignac number, because 31686945 - 2¹¹ = 31684897 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 31686897 and 31686906.

It is not an unprimeable number, because it can be changed into a prime (31686947) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13812 + ... + 15941.

It is an arithmetic number, because the mean of its divisors is an integer number (3213432).

Almost surely, 2^31686945 is an apocalyptic number.

It is an amenable number.

31686945 is a deficient number, since it is larger than the sum of its proper divisors (19727967).

31686945 is a wasteful number, since it uses less digits than its factorization.

31686945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29832.

The product of its digits is 155520, while the sum is 42.

The square root of 31686945 is about 5629.1158275523. The cubic root of 31686945 is about 316.4415161636.

The spelling of 31686945 in words is "thirty-one million, six hundred eighty-six thousand, nine hundred forty-five".