As I mentioned, I don't have it fully mapped out.
I think it puts (x - 499) is a perfect nth power as the highest priority. The other possibility is (x+499) is a perfect nth power. I haven't been able to test which one is higher since those would only both be available for the same number for specific values of x.
Using some prime numbers away from 910, I did get these clues just now:
(x+927)'s largest prime divisor is 167
(x+893)'s largest prime divisor is 601
(x+933)'s largest prime divisor is 97
(x+953)'s largest prime divisor is 23
It preferred those to (963-x) is prime. 910 + 963 = 1873 is a prime number. Same if I tried 957 as 1867 is prime.
I don't recall it not giving "x is a multiple of (499 - x)" when that is an option and it can't do the nth-power clue. It does that for 912, 913, 920, 923, 975, and other number today. It does prefer that to (499 - x) is prime clue.
My only other discovery just now is that if I am 1 away from the solution, the game breaks. Hitting <enter> will cause it to become unresponsive. I can reload the game and make a new guess, however. I will report that bug in a different thread. I don't think I had ever been one away before, so I don't know if this bug is new or not.