The number 666 is the Carbon atom, and man.
Carbon-12 has six protons, six neutrons, and six electrons. Carbon is found in abundance in the stars and as Carl Sagan once said, "We're made of star stuff".
Carbon comes from the Latin word "carbo", which itself is for charcoal or coal.
Isaiah 6:6 - "Then one of the seraphim flew to me with a live coal in his hand, which he had taken with tongs from the altar."
Seraphim are defined (under Christian theology) as:
"an angelic being, regarded in traditional Christian angelology as belonging to the highest order of the ninefold celestial hierarchy, associated with light, ardor, and purity."
(Source: Google Dictionary)