It depends how often the site is updated, and maybe some other things. I'm afraid it's going to take a while before those pages stop turning up in searches, because even after the search spiders visit again and update google's info, it'll keep the old data indexed for a while so it'll still come up in searches. I'm guessing that your number will produce results until the spiders have been there twice and not found it.
I don't think it's something you need to worry about though unless you know some pretty stalkery people. I sometimes google a number to see if I can find out anything about someone who's contacted me, but I don't see why I'd do it with someone I know unless I was trying to work out what they were up to. Plus it's your old number which presumably most of your friends and family don't even have any more.
If you're still worried, you could try flooding the results by using that number in classified ads and anything else you can think of, in the hope of pushing down the old pages further than someone would look. That also gives you a possible get-out of "this crazy girl wanted to buy some shoes from me but I'd already sold them, so she put my phone number on all these weird sites. Joke's on her though, since it's just my secondary phone. I just get a few weird calls sometimes when I'm having a clearout!"