Leonard Farber, M.D.
NPI 1639185838 · Radiation Oncology Physician · Fullerton, CA
Enrolled with Medicare as Practitioner - Radiation Oncology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Leonard Farber, M.D. is a Radiation Oncology Physician provider in Fullerton, CA (NPI 1639185838).
Provider details
- NPI number
- 1639185838
- Entity type
- Individual
- Primary specialty
- Radiation Oncology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- Yes
- License
- 210306 (NY)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure33% of score
19 yrs in NPPES registry
- Profile completeness33% of score
100% of core fields populated
- Practice footprint20% of score
3 documented practice locations
- Open Payments transparency13% of score
Has Open Payments disclosures (2024)
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$44 across 1 record (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Additional practice locations (2)
- 21 West BroadwayNew York, NY 10007Phone: (212) 300-0663Fax: (917) 210-3285
- 21 West BroadwayNew York, NY 10007Phone: (212) 300-0663Fax: (917) 210-3285
Registry dates
- Enumerated
- 2006-07-31
- Last updated
- 2018-04-10
Frequently asked questions
- What is Leonard Farber's NPI number?
- Leonard Farber's National Provider Identifier (NPI) is 1639185838, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Leonard Farber's specialty?
- Leonard Farber is listed in the NPPES registry with a primary specialty of Radiation Oncology Physician (Allopathic & Osteopathic Physicians).
- Where is Leonard Farber located?
- Leonard Farber's practice location on file with NPPES is 2151 N Harbor Blvd Ste 1500, Fullerton, CA 92835-3823.
- What is Leonard Farber's phone number?
- The practice phone number listed in the NPPES registry for Leonard Farber is (714) 446-5632.
- Does Leonard Farber accept Medicare?
- Leonard Farber is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Leonard Farber's NPI active?
- Yes — Leonard Farber's NPI (1639185838) is active in the NPPES registry as of the last update on 2018-04-10.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.