We can see here that it is best to understand what NPI number is and that it is not to be given out witout authorisation.
The NPI number is a unique identification number used by healthcare providers in the United States. It's typically associated with healthcare professionals for billing, administrative, and identification purposes.
If one is seeking the NPI number of a healthcare provider, I would recommend that one contact the provider directly, search for their information in official medical directories or databases, or reach out to the relevant healthcare authorities or organizations that maintain such records.