Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Mark Aaron Denby, LMSW MASTER
Social Worker in Gaithersburg, MD · enumerated 2024.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1699511873
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Registry record
Entity type Individual (Type 1)
Name Mark Aaron Denby
Credential LMSW MASTER
Sex Male
Practice address 232 Main St, Gaithersburg, MD, 20878
Phone (240) 912-4894
Enumeration date Jul 8, 2024
Last updated in NPPES Jul 8, 2024
Taxonomy & licenses
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.
Frequently asked questions
Where does Mark Denby practice?
The practice location on file with NPPES is in Gaithersburg, MD. Providers can have multiple locations; NPPES lists the primary practice address.
What is the NPI number for Mark Denby?
The National Provider Identifier (NPI) for Mark Denby is 1699511873, a Type 1 (individual) record in the CMS NPPES registry.
Other providers at this practice address
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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2024-07-08.