IMEI number is a unique number which can be found on the device's box, by dialing a code, or in the About Device. Find IMEI Number on Galaxy S4 and Note 3 by doing as follows:
1. Open Settings application and go to More tab
2. Scroll down and open About Device.
3. Open Status and find IMEI Number.
You can also dial *#06# and the IMEI Number of your device will appear
Read More Galaxy S4 Tips and Tricks