Squares of prime numbers have exactly three factors.
Numbers with exactly three factors are squares of prime numbers.
There are an infinite number of them. 8 has three prime factors, 30 is the first with three distinct prime factors.
Squares of primes.
A number has exactly three factors if and only if it is the square of a prime number.
By definition, a prime number has exactly two factors. So, there are no prime numbers with exactly three factors.
There are no prime numbers with three factors. By definition, a prime number has exactly two factors - 1 and itself.
Numbers with three factors are squares of primes. So: 4, 9, 25
Numbers with three factors are squares of primes: 4, 9, 25
4, 9 and 25.
There are three of them with exactly five factors.
Numbers having exactly three factors are the squares of prime numbers. Examples of these numbers greater than 100 are 121, 169, 289, 361, 529, 841, etc.