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Also known as the number 21, 1*21, 21*1, twenty-one, twenty one, ㉑
natural number
AI overview
21 is a whole number that comes after 20 and before 22 in the sequence of counting numbers. It is the product of multiplying 3 by 7, making it a composite number with practical applications in mathematics and everyday contexts like telling time and measuring.
AI-generated from the Wikipedia summary — may contain errors.