2x21

2x21 is a mathematical expression consisting of the integers 2 and 21 separated by the multiplication sign (×). In standard arithmetic, 2×21 equals 42. The form can be read as “two by twenty-one” and is commonly used to indicate a product or, in some contexts, a two-dimensional size.

In number theory and arithmetic terms, 42 is the product 2×3×7. It is an even, composite number with divisors including 1, 2, 3, 6, 7, 14, 21, and 42. The factorization highlights its composition from the primes 2, 3, and 7, and it appears in various mathematical contexts such as divisibility, greatest common factor discussions, and combinatorial calculations.

The notation 2×21 can also describe dimensions for rectangular grids or arrays, such as a grid with 2 rows and 21 columns, which contains 42 individual cells. This usage is common in puzzles, seating plans, and simplified design layouts, where the two-by-twenty-one dimension helps convey area, capacity, or arrangement.

Beyond pure mathematics, 2×21 can appear as a model number, part identifier, or designation in engineering, electronics, or manufacturing, where the exact meaning depends on the context and accompanying specifications. In such cases, the term does not denote a numerical result by itself but rather a label used to distinguish a particular item or configuration.

See also: 42; 2 (multiplication); times symbol.