6663 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes.
It is a D-number.
It is a Duffinian number.
6663 is a lucky number.
It is a plaindrome in base 14.
It is a nialpdrome in base 10.
It is a congruent number.
26663 is an apocalyptic number.
6663 is a wasteful number, since it uses less digits than its factorization.
6663 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 2224.
The square root of 6663 is about 81.6272013486. The cubic root of 6663 is about 18.8172694794.
The spelling of 6663 in words is "six thousand, six hundred sixty-three".