The applet will do the following:
1)Factorize the number n
2)Decompose n in sum of two squares in all possible ways (if possible)
3)Find all AP of squares which have n² as middle number.

Limitations:

If the number has two or more very large prime factors (16+ digits) the factorization can take a long time. (using Pollard's rho algorithm)
If there are many (10000+) different arithmetic progressions the browser can run out of memory. You can configure the max memory for applets, but this is not an easy setting to change and is different in each browser.
For numbers with less than 40 digits there should not be any problems. If the factorization has not been completed in 10 minutes there is a good chance it
will take much longer or the applet has run out of memory. If factorization is your primary focus, go to the best factorization applet on the net:
Factorization using the Elliptic Curve Method.