The first three prime numbers (2, 3, and 5) are unique in that all other primes, starting with 7, can be constructed from them using the formula x^n * y^n +or- z^n, where x=2; y=3; and z=5. This formula generates the set of all numbers not divisible by 2, 3 or 5, which, by definition, includes all primes >5 (For example, x^2 * y - z, or 2^2 * 3 - 5 = 7).
squares of prime numbers
41,43, and 47 are all prime numbers. so there are three prime numbers between 40 and 50
The only two prime factors of 18 are: 2, 3
The number 2 is the only even prime number - all other even numbers are divisible by 2.
That's an infinite list.
56 does not have only three prime factors.
Squares of prime numbers have only three factors.
squares of prime numbers
The only prime number divisible by three is three itself.
The numbers with only three factors are squares of prime numbers.
prime squares
7, 13, and 17
41,43, and 47 are all prime numbers. so there are three prime numbers between 40 and 50
225 cannot be factorised into the product of only 3 prime numbers.
The only two prime factors of 18 are: 2, 3
The number 2 is the only even prime number - all other even numbers are divisible by 2.
Because if x and y differ by three, then either x or y has to be an even number. The only even prime is 2.