28
A composite number is a number that is not a prime number, ie it has more than two distinct factors. The factors of 25 are 1, 5, 25 - three distinct factors.
27
840
840
43 is a prime number with only two factors whereas 25 is a composite number with more than two factors
28
840
For common factors you need more than one number.
84 has 12 factors.
25 is a composite number because it has more than two factors
It has more than two factors.
200