What is sum 18?

The number 18 is an even integer number that comes after 17 and before 19. It is divisible by 1, 2, 3, 6, 9, and 18. The sum of the digits in 18 is 9, which makes it a multiple of 9. In Roman numerals, 18 is represented as XVIII. The atomic number of argon is 18. 18 is a popular age for legal status changes, such as voting and driving in many countries. In some cultures, the number 18 is considered lucky or auspicious.