It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-18209 is a prime.
It is a Duffinian number.
It is a plaindrome in base 15.
It is a nialpdrome in base 12.
218209 is an apocalyptic number.
It is an amenable number.
18209 is a wasteful number, since it uses less digits than its factorization.
18209 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 270.
The square root of 18209 is about 134.9407277289. The cubic root of 18209 is about 26.3084562725.
The spelling of 18209 in words is "eighteen thousand, two hundred nine".