31686228 has 72 divisors (see below), whose sum is σ = 94948672. Its totient is φ = 9051264.

The previous prime is 31686169. The next prime is 31686233. The reversal of 31686228 is 82268613.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nialpdrome in base 9.

It is a junction number, because it is equal to n+sod(n) for n = 31686192 and 31686201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4476 + ... + 9132.

Almost surely, 2^31686228 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31686228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47474336).

31686228 is an abundant number, since it is smaller than the sum of its proper divisors (63262444).

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

31686228 is a wasteful number, since it uses less digits than its factorization.

31686228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4683 (or 4669 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 31686228 is about 5629.0521404585. The cubic root of 31686228 is about 316.4391293733.

The spelling of 31686228 in words is "thirty-one million, six hundred eighty-six thousand, two hundred twenty-eight".