There is no way we can assist you in tracking your device by that number. Unless you had tracking software on the phone, or were using a tracking service there is no way you can track it yourself.
You can try contacting your service provider/carrier and see if they can assist you. No guarantees though. You should also have them turn off the service to the device, so that someone doesn't run up your bill.
Then you should log into all accounts you accessed from that device and change all your passwords, before someone can access them and change them on you.