A "passport number" is a unique identification code assigned to each passport. It is used to identify and keep track of an individual's passport information. Full definition
You must give them your complete name and passport number in order to be be put on the list. (anywhere.com)
Please write in Notes: New passport number will be send. (sastravelperu.com)
Legal risks: Users on a financial services blockchain must be identifiable entities, perhaps via something like a single digital passport number. (morganstanley.com)