91980 has 72 divisors (see below), whose sum is σ = 323232. Its totient is φ = 20736.

The previous prime is 91969. The next prime is 91997. The reversal of 91980 is 8919.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 7.

It is an unprimeable number.

91980 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 23 ways as a sum of consecutive naturals, for example, 1224 + ... + 1296.

2⁹¹⁹⁸⁰ is an apocalyptic number.

91980 is a gapful number since it is divisible by the number (90) 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 91980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161616).

91980 is an abundant number, since it is smaller than the sum of its proper divisors (231252).

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

91980 is a wasteful number, since it uses less digits than its factorization.

91980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 91980 is about 303.2820469464. The cubic root of 91980 is about 45.1403028442.

It can be divided in two parts, 919 and 80, that added together give a palindrome (999).

The spelling of 91980 in words is "ninety-one thousand, nine hundred eighty".