It is a happy number.
18381 is nontrivially palindromic in base 10.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is an Ulam number.
It is an alternating number because its digits alternate between odd and even.
18381 is a lucky number.
It is a plaindrome in base 14 and base 16.
It is a congruent number.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 18381.
218381 is an apocalyptic number.
18381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.
It is an amenable number.
18381 is a wasteful number, since it uses less digits than its factorization.
18381 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 571.
The square root of 18381 is about 135.5765466443. The cubic root of 18381 is about 26.3910323077.
The spelling of 18381 in words is "eighteen thousand, three hundred eighty-one".