Categories of Numbers



Prime Numbers

Numbers having factors and number itself are known as prime numbers.
As for example, take number .
Factors of are and
Therefore, is a prime number.


Composite Numbers

Composite numbers are numbers which have at least one factor other than number itself and .
Examples of composite number are   , , .
Factors of are


Perfect Numbers

Perfect numbers are positive integers that is exactly equal to the sum of its perfect positive divisors i.e. sum of positive divisors excluding the number itself.
For example :-
Divisors of  are and
Perfect divisors of   are and
So, is a perfect square.