The On-Line Encyclopedia of Integer Sequences. 'Sequence A006753 (Smith (or joke) numbers: composite numbers n such that sum of digits of n is equal to the sum of digits of prime factors of n (counted with multiplicity).)'.
In Christianity, 666 is referred to in (most manuscripts of) chapter 13 of the Book of Revelation of the New Testament as the ' number of the beast.' In mathematics Ħ66 is the sum of the first thirty-six natural numbers, which makes it a triangular number: ∑ i = 1 36 i = 1 + 2 + 3 + ⋯ + 34 + 35 + 36 = 666.
