Naili Chen, D.O., MPH, MASC
Naili Chen, D.O., MPH, MASC is an Internal Medicine Physician in Lancaster, CA, registered under NPI 1649251661. This provider registers 5 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 44439 17TH ST W, Lancaster, CA 93534. 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 |
|---|---|---|
| OS-009459-L | PA | Internal Medicine Physician |
| 20A7408 | CA | Preventive Medicine/Occupational… |
| OS-009459L | PA | Hospitalist Physician |
| 20A7048 | CA | Hospitalist Physician |
| 20A7408 | CA | Emergency Medical Services (Emergency… |
| 20A7408 | CA | Aerospace Medicine Physician |
| 20A7408 | CA | Internal Medicine Physician primary |
Licences are recorded in 2 states: PA, CA. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
Licensed in 2 states
This provider holds licences in 2 states: California and Pennsylvania. The practice address on file is in Lancaster, CA, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- 20A7408
- Specialty
- Preventive Medicine/Occupational…
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Internal Medicine covers
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs. NUCC Health Care Provider Taxonomy, code 207R00000X
All registered taxonomy codes
This provider registers 7 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207R00000X | Internal Medicine Physician | OS-009459-L | PA | |
| 2083P0500X | Preventive Medicine/Occupational Environmental Medicine Physician Preventive Medicine/Occupational Environmental Medicine | 20A7408 | CA | |
| 208M00000X | Hospitalist Physician | OS-009459L | PA | |
| 208M00000X | Hospitalist Physician | 20A7048 | CA | |
| 207PE0004X | Emergency Medical Services (Emergency Medicine) Physician Emergency Medical Services | 20A7408 | CA | |
| 2083A0100X | Aerospace Medicine Physician Aerospace Medicine | 20A7408 | CA | |
| 207R00000X | Internal Medicine Physician | 20A7408 | CA | primary |
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 | 1649251661 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Nov 8, 2005 |
| Last updated | May 20, 2026 |
| Status | Active |
| Sole proprietor | Yes |
| Gender | Male |
| Credential | D.O., MPH, MASC |
| Practice address |
44439 17TH ST W Lancaster, CA 93534 (661) 729-8655 |
| Other identifiers |
20A7408
· Other (CA) |
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 | 6 | 4 | 9 | 2 | 5 | 1 | 6 | 6 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 6 | 8 | 9 | 4 | 5 | 2 | 6 | 3 |
Sum = 69 · next multiple of 10 = 70 · check digit = 1 · actual last digit = 1
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.