18000 has 60 divisors (see below), whose sum is σ = 62868. Its totient is φ = 4800.

The previous prime is 17989. The next prime is 18013. The reversal of 18000 is 81.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 576 + 17424 = 24^2 + 132^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (9).

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

It is a nialpdrome in base 12 and base 15.

It is a zygodrome in base 15.

It is a congruent number.

It is an unprimeable number.

18000 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 (5) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3598 + ... + 3602.

2¹⁸⁰⁰⁰ is an apocalyptic number.

18000 is a gapful number since it is divisible by the number (10) 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 18000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31434).

18000 is an abundant number, since it is smaller than the sum of its proper divisors (44868).

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

18000 is a wasteful number, since it uses less digits than its factorization.

18000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29 (or 10 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 18000 is about 134.1640786500. The cubic root of 18000 is about 26.2074139421.

Adding to 18000 its reverse (81), we get a palindrome (18081).

It can be divided in two parts, 1 and 8000, that added together give a triangular number (8001 = T₁₂₆).

The spelling of 18000 in words is "eighteen thousand".