17, 19, and 23.
All the other numbers have more than two factors.
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How many numbers are in 28
No, because 28 can only be calculated as a product in the following ways: 1 x 28 2 x 14 4 x 7 In the above cases, 28, 14 and 4 are all non-prime numbers, which means that 28 cannot be a product of 2 prime numbers alone.
28 = 2x2x7
The only prime factor of 16 is 2.
The sum of the first five prime numbers is 28. The sum of the cubes of the first three prime numbers is 160. The average of 28 and 160 is 94.