A Prime number is one who's only factors are One and Itself. Sometimes people will say a number is 'divisible by X', which means that X is a factor of the number.
There are several tests for certain factors that you can do quickly, if you memorize them. For example, 2100 has several factors that I can spot without doing any division: It has zero in the ones digit. This tells me that it's divisible by 5, also 0 in ones digit tells me that it's even (divisible by 2). The 'sum of the digits' is a multiple of three, so the number is also a multiple of three (2 + 1 + 0 + 0 = 3).
composite
2,100 is a Composite Number.
No, all even numbers greater than two are composite.
neither prime or composite
It is prime
It would be impossible to list them all, since numbers go on forever, but here are some of them: 2 - Prime 3 - Prime 4 - Composite 5 - Prime 6 - Composite 7 - Prime 8 - Composite 9 - Composite 10 - Composite 11 - Prime 12 - Composite 13 - Prime 14 - Composite 15 - Composite 16 - Composite 17 - Prime 18 - Composite 19 - Prime 20 - Composite 21 - Composite 22 - Composite 23 - Prime 24 - Composite 25 - Composite 26 - Composite 27 - Composite 28 - Composite 29 - Prime 30 - Composite 31 - Prime 32 - Composite 33 - Composite 34 - Composite 35 - Composite 36 - Composite 37 - Prime 38 - Composite 39 - Composite 40 - Composite 41 - Prime 42 - Composite 43 - Prime 44 - Composite 45 - Composite 46 - Composite 47 - Prime 48 - Composite 49 - Composite 50 - Composite
As a product of its prime factors in exponents it is: 22*3*52*7 = 2100
4, composite. 67, prime.
Prime
1 is special 2 prime 3 prime 4 composite 5 prime 6 composite 7 prime 8 composite 9 composite 10 composite 11 prime 12 composite ext.
5 prime, 25 composite.
One is not prime and not composite.