I have approximately 16500 USD in my bank account, but is it enough to get study permit? My university cost around 18000 USD per year and I have already paid half.
You should have first year tuition + $10K for living expenses + $2-3K for travel expenses. If you've already paid some of your tuition - then you would deduct that from the total. So you are probably a few K short of the ideal amount you should show.
In total, you should have around US$25 as funds, but the more you have, the better... I would also think you are kind of short. At least some US$ 2000 more