What is "composite number"

Composite \Com*pos"ite\ (?; 277), a. [L. compositus made up of parts, p. p. of componere. See Compound, v. t., and cf. Compost.]

1. Made up of distinct parts or elements; compounded; as, a composite language.

   Happiness, like air and water . . . is composite.
   --Landor.

2. (Arch.) Belonging to a certain order which is composed of the Ionic order grafted upon the Corinthian. It is called also the Roman or the Italic order, and is one of the five orders recognized by the Italian writers of the sixteenth century. See Capital.

3. (Bot.) Belonging to the order Composit[ae]; bearing involucrate heads of many small florets, as the daisy, thistle, and dandelion.

   Composite carriage, a railroad car having compartments of different classes. [Eng.]

   Composite number (Math.), one which can be divided exactly by a number exceeding unity, as 6 by 2 or 3..

   Composite photograph or Composite portrait, one made by a combination, or blending, of several distinct photographs.
   --F. Galton.

   Composite sailing (Naut.), a combination of parallel and great circle sailing.

   Composite ship, one with a wooden casing and iron frame.

n. A number that can be expressed as a product of at least two numbers other than itself and 1.

n. an integer that is divisible without remainder by at least one positive integer other than itself and one

A composite number is a positive integer that can be formed by multiplying together two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than 1 and itself. Every positive integer is composite, prime, or the unit 1, so the composite numbers are exactly the numbers that are not prime and not a unit.

For example, the integer 14 is a composite number because it is the product of the two smaller integers 2 × 7. Likewise, the integers 2 and 3 are not composite numbers because each of them can only be divided by one and itself.

The composite numbers up to 150 are

4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 128, 129, 130, 132, 133, 134, 135, 136, 138, 140, 141, 142, 143, 144, 145, 146, 147, 148, 150.

Every composite number can be written as the product of two or more (not necessarily distinct) primes. For example, the composite number 299 can be written as 13 × 23, and the composite number 360 can be written as 2 × 3 × 5; furthermore, this representation is unique up to the order of the factors. This fact is called the fundamental theorem of arithmetic.

There are several known primality tests that can determine whether a number is prime or composite, without necessarily revealing the factorization of a composite input.