Nothing special.
They are squares of prime numbers.
24
The square of any prime number has exactly three factors: 22, 32, 52, etc.
The answer is 25 because it has the factors 1,5,25! :)
I found 105,63 and 27
25
The smallest number that has exactly three factors is 4.
24
The square of any prime number has exactly three factors: 22, 32, 52, etc.
By definition, a prime number has exactly two factors. So, there are no prime numbers with exactly three factors.
27
105
4, 9, 25
49 has exactly 3 factors (1, 7, and 49) and is greater than 40 and less than 60.
3*5*7*9 = 945 ...check if any number less than that has exactly four distinct factors.
It is 30.
105 is one such number.
The answer is 25 because it has the factors 1,5,25! :)