31840 has 24 divisors (see below), whose sum is σ = 75600. Its totient is φ = 12672.

The previous prime is 31817. The next prime is 31847. The reversal of 31840 is 4813.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a nialpdrome in base 14.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31847) by changing a digit.

31840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61 + ... + 259.

It is an arithmetic number, because the mean of its divisors is an integer number (3150).

2³¹⁸⁴⁰ 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 31840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37800).

31840 is an abundant number, since it is smaller than the sum of its proper divisors (43760).

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

31840 is a wasteful number, since it uses less digits than its factorization.

31840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214 (or 206 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 31840 is about 178.4376641856. The cubic root of 31840 is about 31.6950192362.

It can be divided in two parts, 318 and 40, that multiplied together give a triangular number (12720 = T₁₅₉).

The spelling of 31840 in words is "thirty-one thousand, eight hundred forty".