yes. you'll have to create a new "Call Rerouting Always Alternatives" definition that points to 4270 in the "Call Rerouting Always Alternatives" form. Then, in call rerouting, set 4352 to go to that newly created index.
I'm not sure how to find a non-prime number. Could try user and device config, and search for the name "phantom", and hope that whoever created it put it in that way, then you can delete that number and use a speedcall... OR do the call rerouting like I mentioned above.