"Hidden" in Plain Sight: "6-6-6"....Why, Why, Why?

I ask questions...It's Even in a light bulb...Nothing "wrong" with a "Number" like 666, mind you, it's used in math equations all the time. Somewhere along the way, the Number 666 has been hijacked and is used to Anti-virtue signal to other "Cult members" if you will. New owners of "666 Fifth Ave" changed it to "660" Fifth Ave...Now why do you suppose they did that?