Prime numbers definition:
So which numbers are called prime numbers?
Numbers are called prime numbers if
Note, only natural numbers can be prime numbers.
Now we know which numbers are called prime numbers and we can give examples of prime numbers.
Examples of prime numbers:
All of these numbers are natural, greater than one and can be divided evenly only by one and itself.
So you see, mathematical definition of a prime number is very simple.
Prime numbers are often called primes.
Now the question: is 4 a prime number?
No, four is not a prime number because it can be divided evenly by one, by itself and by two.