31638 has 8 divisors (see below), whose sum is σ = 63288. Its totient is φ = 10544.

The previous prime is 31627. The next prime is 31643. The reversal of 31638 is 83613.

It is a sphenic number, since it is the product of 3 distinct primes.

31638 is an admirable number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

31638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2631 + ... + 2642.

It is an arithmetic number, because the mean of its divisors is an integer number (7911).

2³¹⁶³⁸ is an apocalyptic number.

31638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31644).

31638 is a wasteful number, since it uses less digits than its factorization.

31638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5278.

The product of its digits is 432, while the sum is 21.

The square root of 31638 is about 177.8707395836. The cubic root of 31638 is about 31.6278502537.

The spelling of 31638 in words is "thirty-one thousand, six hundred thirty-eight".