289, 343, and 361 can actually be played in-game through a sequence like 73/-200/extractor taking -200/INPUT 2 as 73/-200/65/X-stone. You can get as high as 427 by playing the first 73 in the previous turn.
they dont do anything tho sad
Can also get 457 (which I am pretty sure is a prime number) by using 43 on the 2nd 73
I cannot think of any way to get anything higher than that
