Date: Thu, 17 Sep 1998 23:29:25 -0400 To whom it may concern, I have difficulty in getting the solution to the following question: Find 5 numbers that have exactly 5 factors. I got 16, 81 but couldn't find the rest. I believe that in order to have 5 factors, it has to be a square number. Isn't it true? I guess there may be a pattern to this.
Thanks for your help.
Hi Derek If p is a prime does have 5 factors? Since p is a prime, if b divides then b must be a power of p also, with its exponent at most 4. Thus and a is 0, 1, 2, 3 or 4. Hence has 5 factors. Are primes to the fourth power the only numbers with exactly 5 factors?
Cheers, |

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