666 (number)

666 is the number that preceeds 665 and proceeds 667. It is known as the illuminati or Number of the Beast.

The prime factorization of the number 666 is $2*3^2 * 37$.

666 is the sum of the first 36 natural numbers $(\sum_{k=1}^{36}k)$. It is also the sum of the squares of the first 7 primes (ie.$2^2 + 3^2 + 5^2 + 7^2 + 11^2 + 13^2 + 17^2$)

When you flip over 666, you get 999, the biggest 3 digit number.