I understand why you might want to do this, but I'm afraid it's not possible to remove the question number. This is how Q2A identifies the page request, and the rest of the URL is there for search engines.
In theory the question could be identified based on the text only, but there are so many possible ways for this to go wrong (duplicate questions, some questions are shortened for the URL, non-English characters, URLs getting cut off in emails) that it wouldn't be a reliable solution.