31689936 has 90 divisors (see below), whose sum is σ = 92041170. Its totient is φ = 10177920.

The previous prime is 31689923. The next prime is 31689941. The reversal of 31689936 is 63998613.

It can be written as a sum of positive squares in only one way, i.e., 31136400 + 553536 = 5580^2 + 744^2 .

It is a nude number because it is divisible by every one of its digits.

It is a nialpdrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 31689891 and 31689900.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 138270 + ... + 138498.

Almost surely, 2^31689936 is an apocalyptic number.

31689936 is a gapful number since it is divisible by the number (36) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31689936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46020585).

31689936 is an abundant number, since it is smaller than the sum of its proper divisors (60351234).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31689936 is a wasteful number, since it uses less digits than its factorization.

31689936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305 (or 265 counting only the distinct ones).

The product of its digits is 209952, while the sum is 45.

The square root of 31689936 is about 5629.3814935568. The cubic root of 31689936 is about 316.4514723858.

The spelling of 31689936 in words is "thirty-one million, six hundred eighty-nine thousand, nine hundred thirty-six".