91800 has 96 divisors (see below), whose sum is σ = 334800. Its totient is φ = 23040.

The previous prime is 91781. The next prime is 91801. The reversal of 91800 is 819.

91800 is nontrivially palindromic in base 14.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91801) by changing a digit.

91800 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, 5392 + ... + 5408.

2⁹¹⁸⁰⁰ is an apocalyptic number.

91800 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 91800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (167400).

91800 is an abundant number, since it is smaller than the sum of its proper divisors (243000).

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

91800 is a wasteful number, since it uses less digits than its factorization.

91800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42 (or 27 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 91800 is about 302.9851481509. The cubic root of 91800 is about 45.1108378861.

91800 divided by its product of nonzero digits (72) gives a triangular number (1275 = T₅₀).

The spelling of 91800 in words is "ninety-one thousand, eight hundred".