31980 has 48 divisors (see below), whose sum is σ = 98784. Its totient is φ = 7680.

The previous prime is 31973. The next prime is 31981. The reversal of 31980 is 8913.

It is a Smith number, since the sum of its digits (21) coincides with the sum of the digits of its prime factors.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 760 + ... + 800.

It is an arithmetic number, because the mean of its divisors is an integer number (2058).

2³¹⁹⁸⁰ is an apocalyptic number.

31980 is a gapful number since it is divisible by the number (30) 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 31980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49392).

31980 is an abundant number, since it is smaller than the sum of its proper divisors (66804).

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

31980 is a wasteful number, since it uses less digits than its factorization.

31980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 31980 is about 178.8295277632. The cubic root of 31980 is about 31.7414054899.

The spelling of 31980 in words is "thirty-one thousand, nine hundred eighty".