When the number is a square of a Prime number. Of course, it will have a repeated factor, but it will still only have 3 distinct factors. 4, 9, 25, 49, 121 are some examples.
A factor = a number which can be divided into the given number with no remainder so no, 3 is not a factor of 20
202
It's a perfect square.
Odd. I determined my answer by looking at the number of factors of a square number.
The distinct factors of 75 are 1, 3, 5, 15, 25, 75.
The difference is one.
3 is a prime number because it has exactly two distinct factors. The only factors of a prime number are 1 and itself. The only factors of 3 are 1 and 3, so it is a prime number.
Seven distinct factors.
2. 2 and 3
There are an infinite number of them. 8 has three prime factors, 30 is the first with three distinct prime factors.
3*5*7*9 = 945 ...check if any number less than that has exactly four distinct factors.
2*3*5 = 30
no. 513=3^3×19 (4 prime factors, 2 distinct)
2 x 3 x 5 = 30
3
There is more than one possible answer. The prime factors of 16 are 2, 2, 2, and 2. It has four prime factors, but only one distinct prime factor. The prime factors of 24 are 2, 2, 2, and 3. It has four prime factors, but only two distinct prime factors. The prime factors of 36 are 2, 2, 3, and 3. It has four prime factors, but only two distinct prime factors. The prime factors of 40 are 2, 2, 2, and 5. It has four prime factors, but only two distinct prime factors. The prime factors of 54 are 2, 3, 3, and 3. It has four prime factors, but only two distinct prime factors. The prime factors of 56 are 2, 2, 2, and 7. It has four prime factors, but only two distinct prime factors. The prime factors of 60 are 2, 2, 3, and 5. It has four prime factors, but only three distinct prime factors. The prime factors of 81 are 3, 3, 3, and 3. It has four prime factors, but only one distinct prime factor. The prime factors of 84 are 2, 2, 3, and 7. It has four prime factors, but only three distinct prime factors. The prime factors of 88 are 2, 2, 2, and 11. It has four prime factors, but only two distinct prime factors. The prime factors of 90 are 2, 3, 3, and 5. It has four prime factors, but only three distinct prime factors.
Three distinct prime factors.