SOLUTION: How many different perfect squares are factors of 2007^2007?

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Question 1150159: How many different perfect squares are factors of 2007^2007?
Found 2 solutions by greenestamps, ikleyn:
Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


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(corrected response, thanks to tutor @ikleyn for pointing out the obvious error....)
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The sum of the digits of 2007 is 9, so the number is divisible by 9:

2007+=+3%2A3%2A223

223 is prime, so we have the prime factorization of 2007:

2007+=+%283%5E2%29%28223%5E1%29

Then

2007%5E2007+=+%283%5E4014%29%28223%5E2007%29

A perfect square factor of the number has to be of the form

%283%5Ea%29%28223%5Eb%29

Where a and b are even integers, with 0 <= a <= 4014 and 0 <= b <= 2007.

That gives us 2008 choices for a and cross%282007%29 1004 choices for b; the number of perfect square factors of the number is then cross%282008%2A2007+=+4030056%29 2008*1004 = 2016032.


Answer by ikleyn(52851) About Me  (Show Source):
You can put this solution on YOUR website!
.

The logic and the development of the solution by @greenestamps are  ALMOST correct,  except the last line,
which should be edited.


The correct form of the last two lines and the correct answer are as follows:

    Where a and b are even integers, with 0 <= a <= 4014 and 0 <= b <= 2007.

    That give us 2008 choices for a and %282007%2B1%29%2F2 = 2008%2F2 = 1004 choices for b; 

    the number of perfect square factors of the number is then 2008*1004 = 2016032.

Again,  the correct answer for the number of perfect square factors of  2007%5E2007  is  2016032.