Those are prime numbers.
In any list of distinct numbers, one will be greater than the others. In the list of common factors, one will be the greatest.
Just 36.
There are an infinite number of them. 8 has three prime factors, 30 is the first with three distinct prime factors.
4 and 9
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.
A positive integer with exactly two distinct factors.
Any composite number. Examples: 4 and 9 . . . (three factors) 6, 8, and 10 . . . (four factors) 12 . . . (six factors) 60 . . . (twelve factors)
Numbers with exactly three factors are squares of prime numbers.
Squares of prime numbers have exactly three factors.
All numbers that are the square of primes have exactly 3 factors.
All numbers that have exactly two factors are prime numbers whereas composite numbers have more than two factors.
The prime factorization of 20 is 2 x 2 x 5. That's three prime factors; two distinct prime factors.