Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Ralph Maximillian Koenker, M.D.

Diagnostic Radiology Physician in Greenbrae, CA · enumerated 2006.

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

National Provider Identifier

1891734265

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Registry record

Entity type Individual (Type 1)

Name Ralph Maximillian Koenker

Credential M.D.

Sex Male

Practice address 250 Bon Air Rd, Greenbrae, CA, 94904

Phone (415) 925-7000

Enumeration date Jun 4, 2006

Last updated in NPPES Jun 28, 2026

Taxonomy & licenses

2085N0700X Neuroradiology Physician Allopathic & Osteopathic Physicians · License G60981 (CA) Secondary

2085R0202X Diagnostic Radiology Physician Allopathic & Osteopathic Physicians · License G60981 (CA) Primary

2085R0204X Vascular & Interventional Radiology Physician Allopathic & Osteopathic Physicians · License G60981 (CA) Secondary

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
00G609810	Medicaid	CA	-
300121787	Other	CA	RAILROAD MEDICARE
00G609810	Other	CA	BLUE SHIELD
300035771	Other	CA	RAILROAD MEDICARE

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.

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Frequently asked questions

Is NPI 1891734265 active?

Yes, as of the latest NPPES snapshot, NPI 1891734265 is active (record last updated 2026-06-28).

How do I verify Ralph Koenker's NPI record?

Cross-check NPI 1891734265 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

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Marin Community Clinic Federally Qualified Health Center (FQHC) · Greenbrae, CA NPI 1124021738 Aida Calvillo Internal Medicine Physician · Greenbrae, CA NPI 1225031727 Debra Walhof Pediatrics Physician · Greenbrae, CA NPI 1912900499 Georgianna Farren Internal Medicine Physician · Greenbrae, CA NPI 1346249067 Janet Miller-Melka Nurse Practitioner · Greenbrae, CA NPI 1780677963 Dana Huskey Obstetrics & Gynecology Physician · Greenbrae, CA NPI 1538146337 Russell Fritz Diagnostic Radiology Physician · Greenbrae, CA NPI 1679550032 Marin General Hospital General Acute Care Hospital · Greenbrae, CA NPI 1396725677

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2026-06-28.