The beast number or sign of the devil is equal to 666. It is associated with Satan, evil, and bad luck in Western numerology. The number's origin is in Revelation 13:18 from the Christian Bible: "This calls for wisdom. Let the person who has insight calculate the number of the beast, for it is the number of a man. That number is 666." Some translations give 616. A number with 666 digits is called an apocalypse number, and a number of the form 2n containing 666 in its decimal expansion is called an apocalyptic number.