XXI

XXI is the Roman numeral for the number 21. It is formed by X (10) + X (10) + I (1). Beyond simple counting, XXI is used in various formal or ceremonial contexts to designate editions, volumes, regnal numbers, or numbered events, such as the XXI Olympiad, where the Roman numeral marks the 21st edition of the Games.

In contemporary writing, XXI often signals the 21st century. The form XXI is sometimes used in formal or stylistic contexts to refer to the era more succinctly than the phrase “the 21st century,” though everyday usage typically prefers the latter. The numeral may also appear in museums, scholarly works, or architectural inscriptions to convey a sense of tradition or timelessness.

The number 21 holds cultural significance in many societies, including legal and social milestones that vary by jurisdiction. In some places, 21 marks adulthood or the legal drinking age, while in others different ages apply. As a stylistic element, XXI is also employed as a brand name, product line, or title across industries, chosen for its minimal, modern appearance and its association with the Roman numeral tradition.

Overall, XXI functions as both a precise numeric symbol and a versatile stylistic device, appearing in contexts ranging from historical notation to contemporary branding.