Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Brian P O'Sullivan

Internal Medicine Physician in Centennial, CO · enumerated 2007.

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

National Provider Identifier

1801926662

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Registry record

Entity type Individual (Type 1)

Name Dr. Brian P O'Sullivan

Sex Male

Practice address 5555 E Arapahoe Rd, Centennial, CO, 80122

Phone (303) 338-4545

Enumeration date Mar 7, 2007

Last updated in NPPES Jun 3, 2021

Taxonomy & licenses

207R00000X Internal Medicine Physician Allopathic & Osteopathic Physicians · License 43257 (CO) Primary

Other identifiers

Identifier	Type	State	Issuer
35151811	Medicaid	CO	-
015968	Other	-	KAISER-COMMERCIAL NUMBER

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

What specialty is Brian O'Sullivan?

Brian O'Sullivan is registered in NPPES with the primary taxonomy of Internal Medicine Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2021-06-03.