Numerologists say that every number has a specific meaning. Usually, each number represents good and bad qualities, but some people believe there are extremely influential numbers that are the synonym for bad luck. The most common unlucky numbers include 13, 43, 4, and 666. They are associated with evil forces. The luckiest numbers are 7, 9, 11, 12, 13, 17, 18, 19, 23, and 27.