21991385

21991385 is an eight-digit numeric string commonly used as a unique identifier in various information systems. On its own, the sequence does not convey intrinsic meaning; its significance arises from the context in which it is assigned and managed by a specific database, catalog, or workflow.

Possible contexts for the use of such an identifier include archival records, library catalogs, inventory or order systems, manufacturing batches, or healthcare and administrative records. In each case, 21991385 would function as a key that distinguishes a single item or record from all others within a defined scope. Different domains may reuse numeric sequences independently, so identical numbers can appear in separate systems without implying a common item.

In database design, eight-digit identifiers are typically generated by auto-increment mechanisms, unique constraint systems, or randomization methods to ensure uniqueness within a given dataset. They may be stored as numeric types or strings, and some implementations add prefixes, suffixes, or check digits to encode additional information or to improve error detection, though 21991385 itself carries no universal meaning without accompanying metadata.

Limitations of numeric IDs like 21991385 include the lack of descriptive content and reliance on external documentation to interpret what the ID references. Proper usage usually requires a data schema, metadata, or a data dictionary that links the identifier to its corresponding attributes, relationships, and context.

See also: Unique identifier, Primary key, Serial number, Accession number, Cataloging.