81980 has 12 divisors (see below), whose sum is σ = 172200. Its totient is φ = 32784.

The previous prime is 81973. The next prime is 82003. The reversal of 81980 is 8918.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81980.

It is an unprimeable number.

81980 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, 2030 + ... + 2069.

It is an arithmetic number, because the mean of its divisors is an integer number (14350).

2⁸¹⁹⁸⁰ is an apocalyptic number.

It is an amenable number.

81980 is an abundant number, since it is smaller than the sum of its proper divisors (90220).

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 (86100).

81980 is a wasteful number, since it uses less digits than its factorization.

81980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4108 (or 4106 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 81980 is about 286.3214976211. The cubic root of 81980 is about 43.4412824717.

The spelling of 81980 in words is "eighty-one thousand, nine hundred eighty".