You can use Verified by GS1 to see who owns the number.
A GTIN, or Global Trade Item Number, is the number found beneath a barcode and identifies the product its attached to.
If you have the GTIN you would like to check, go to Verified by GS1 and search the number under Verify Product. This will tell you if the number is valid and if there is a company name associated with it. It will also bring up any product information that has been shared by that company's GS1 Member Organisation (Country Office).
If you'd like more information about Verified by GS1 and how you can use it to share your product data, you can read about it here.