18549 has 10 divisors (see below), whose sum is σ = 27830. Its totient is φ = 12312.

The previous prime is 18541. The next prime is 18553. The reversal of 18549 is 94581.

It can be written as a sum of positive squares in only one way, i.e., 18225 + 324 = 135^2 + 18^2 .

It is not a de Polignac number, because 18549 - 2³ = 18541 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a nialpdrome in base 3.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 34 + ... + 195.

It is an arithmetic number, because the mean of its divisors is an integer number (2783).

2¹⁸⁵⁴⁹ is an apocalyptic number.

It is an amenable number.

18549 is a deficient number, since it is larger than the sum of its proper divisors (9281).

18549 is an equidigital number, since it uses as much as digits as its factorization.

18549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241 (or 232 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 18549 is about 136.1947135538. The cubic root of 18549 is about 26.4711921431.

The spelling of 18549 in words is "eighteen thousand, five hundred forty-nine".