Gregory Thalken, MD
Gregory Thalken, MD is a Diagnostic Radiology Physician in Long Beach, CA, registered under NPI 1861547317.
Getting there
The practice address on file is 2801 ATLANTIC AVE, Long Beach, CA 90806. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| C162624 | CA | Diagnostic Radiology Physician primary |
This provider holds licence C162624 issued in CA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Diagnostic Radiology
- PAC ID
- 9830333541
Enrolled in Medicare 17 times, across 17 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Mississippi | I20130919000501 | Practitioner - Diagnostic Radiology |
| Minnesota | I20190109002556 | Practitioner - Diagnostic Radiology |
| California | I20191203001812 | Practitioner - Diagnostic Radiology |
| New Jersey | I20191205001399 | Practitioner - Diagnostic Radiology |
| Nevada | I20200115000214 | Practitioner - Diagnostic Radiology |
| Hawaii | I20201202001675 | Practitioner - Diagnostic Radiology |
| Louisiana | I20210311002800 | Practitioner - Diagnostic Radiology |
| Kentucky | I20210827001486 | Practitioner - Diagnostic Radiology |
| Indiana | I20211011002305 | Practitioner - Diagnostic Radiology |
| Oregon | I20211013002483 | Practitioner - Diagnostic Radiology |
| Arkansas | I20230329001572 | Practitioner - Diagnostic Radiology |
| Illinois | I20230525000848 | Practitioner - Diagnostic Radiology |
| Texas | I20240911000138 | Practitioner - Diagnostic Radiology |
| Alabama | I20250708003145 | Practitioner - Diagnostic Radiology |
| Pennsylvania | I20250825002952 | Practitioner - Diagnostic Radiology |
| Ohio | I20251126004094 | Practitioner - Diagnostic Radiology |
| Michigan | I20260304000252 | Practitioner - Diagnostic Radiology |
Medicare enrolment is recorded as approved under the provider type Practitioner - Diagnostic Radiology. There are 17 separate enrolment records across 17 states (MS, MN, CA, NJ, NV, HI, LA, KY, IN, OR, AR, IL, TX, AL, PA, OH, MI). Multiple enrolments usually mean the provider bills Medicare from more than one practice location, or has kept an earlier enrolment after moving. Each record carries its own enrolment ID, listed above. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Diagnostic Radiology covers
A radiologist who utilizes x-ray, radionuclides, ultrasound and electromagnetic radiation to diagnose and treat disease. NUCC Health Care Provider Taxonomy, code 2085R0202X
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1861547317 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jan 24, 2007 |
| Last updated | May 6, 2026 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
2801 ATLANTIC AVE Long Beach, CA 90806 (562) 933-1550 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 8 | 6 | 1 | 5 | 4 | 7 | 3 | 1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 3 | 1 | 1 | 4 | 5 | 3 | 2 |
Sum = 53 · next multiple of 10 = 60 · check digit = 7 · actual last digit = 7
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.