Question: Find highest "isprime" which Maple can handle

I'd like to find out what number Maple can still calculate the isprime for, and what number will make it go "No thanks, this is madness - ERROR".

I tried isprime (10^100,000,000 + 2), and it can still calculate the result. No prime of course, that's the whole point of the +2.

I tried isprime(10^10ˆ9 + 2) and it crashed.

But what is the tipping number?

I decided I should write a loop, and let maple write away the last number till it crashes. Is this possible? I think I'll need something like

> for n from 5 to ??? do isprime (10ˆn + 2) and ??? end do

This isn't suitable at all, but I cant figure out how to program "to error" or "write away this number"...

I hope the question is clear and look forward to ideas on how to make this work.