What is 21?

21 is a natural number following 20 and preceding 22. In Roman numerals, it is written as XXI. In mathematics, it is classified as an odd number, as it is not divisible by 2.

21 is the atomic number of scandium, a chemical element in the periodic table. It is also the legal drinking age in the United States.

In Blackjack, 21 is the highest possible total of any hand, making it a winning combination. Additionally, there are 21 spots on a standard six-sided die.

The number 21 holds significance in various cultures and traditions. In many countries, it is considered a milestone age, marking the transition to adulthood. In some cultures, turning 21 is celebrated with special rites or ceremonies.

21 has also been featured in popular culture, such as the film "21" based on the true story of a group of MIT students who used their math skills to win big at casinos. Additionally, 21 is often associated with luck or coming of age in literature and media.