I got my iPhone stolen, I don't have product box I have never synced it with iTunes and I also didn't register it on apple support. Is there any chance I can find out the IMEI number of my iPhone?

No. There is no way to trace it with the IMEI number. Since you have failed to do all of the things that could have helped you to trace it, there is nothing anyone can do for you now.

Maybe when you buy the next one you might consider do them then.

With what you have described you have very limited options.

iOS: How to find the serial number, IMEI, MEID, CDN, and ICCID number - http://support.apple.com/kb/HT4061

Your carrier would have a record.

If your iPhone, iPad, or iPod touch is lost or stolen - https://support.apple.com/en-us/HT201472

Report a lost or stolen Apple product - https://support.apple.com/HT204315

If you had activated it and used it with a carrier, that carrier should be able to tell you the IMEI. However, the IMEI is not important when it comes to locating the device. That would be done using Find My iPhone. When you report the theft to the local law enforcement, they need the serial number, which unfortunately, you don't have either.

Your carrier might be able to blacklist the IMEI, preventing the phone being used by somebody else, but that won't help return the phone to you if that was the ultimate object of your question (you did not ask about finding the phone, only the IMEI).

Limnos wrote:

Your carrier might be able to blacklist the IMEI, preventing the phone being used by somebody else, but that won't help return the phone to you if that was the ultimate object of your question (you did not ask about finding the phone, only the IMEI).

That is true, and that could be handled at the same time that the OP calls the carrier and asks about the IMEI number. I think maybe you responded to the wrong person, since I did not ask the original question.