Hexakosioihexekontahexaphobia literally means "fear of the number 666" and usually describes the fear or concern associated with the Number of the Beast.
While it is a popular phobia found in horror movies, this phobia can also be observed in everyday life. In June 2006, some couples voiced concerns over giving birth on June 6 ("6/6/06"). Also, Nancy and Ronald Reagan showed this concern in the 1980s:
|“||[The Reagans] bought the 7,192-square-foot ranch-style house at 666 St. Cloud Road in Bel-Air for $2.5 million. In February, the address was officially changed to 668 on city records because of the "mutual concern" of the Reagans that the old number could be construed as a Biblical reference to Satan...||”|
- "THE REAGANS: First Family Easing Into Private Life", Los Angeles Times, Nov. 19, 1988, particular quote found here