31808 has 28 divisors (see below), whose sum is σ = 73152. Its totient is φ = 13440.

The previous prime is 31799. The next prime is 31817. The reversal of 31808 is 80813.

It is an interprime number because it is at equal distance from previous prime (31799) and next prime (31817).

It is a tau number, because it is divible by the number of its divisors (28).

It is a nialpdrome in base 8 and base 14.

It is a self number, because there is not a number n which added to its sum of digits gives 31808.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 31808.

It is an unprimeable number.

31808 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, 413 + ... + 483.

2³¹⁸⁰⁸ 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 31808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36576).

31808 is an abundant number, since it is smaller than the sum of its proper divisors (41344).

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

31808 is an equidigital number, since it uses as much as digits as its factorization.

31808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90 (or 80 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 31808 is about 178.3479744769. The cubic root of 31808 is about 31.6843975802.

The spelling of 31808 in words is "thirty-one thousand, eight hundred eight".