NPI Portal NPI Lookup & Verification

Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

James A. Mack, MD

Endocrinology, Diabetes & Metabolism Physician in Billings, MT · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1669575445

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)
Name James A. Mack
Credential MD
Sex Male
Practice address 1045 N 30th St, Billings, MT, 59101
Phone (406) 238-2500
Enumeration date Sep 6, 2006
Last updated in NPPES Feb 10, 2022

Taxonomy & licenses

207RE0101X Endocrinology, Diabetes & Metabolism Physician Allopathic & Osteopathic Physicians · License 8739 (MT) Primary
MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier Type State Issuer
00000833 Other MT BCBS PIN
114711100 Other WY MDCD PIN
0019975 Other MT MDCD PIN

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

Is NPI 1669575445 active?
Yes, as of the latest NPPES snapshot, NPI 1669575445 is active (record last updated 2022-02-10).
How do I verify James Mack's NPI record?
Cross-check NPI 1669575445 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Other providers at this practice address

Browse all →

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2022-02-10.