Homonym: 21 (Legal Age)
The number 21 is a natural number that follows 20 and precedes 22. It is often associated with various cultural and mathematical significances, such as being the sum of the first six prime numbers. In many cultures, 21 is considered a milestone age, marking the transition into adulthood and the legal age for drinking alcohol in several countries.
In games, 21 is famously known as the winning score in the card game Blackjack, where players aim to reach this number without exceeding it. Additionally, 21 is the product of 3 and 7, making it a composite number with factors that are both prime.