Mail clients or security gateways sometimes rename attachments with a numeric string if the original name is obscured or needs to be unique.

Use a multi-engine scanner like VirusTotal to check the hash or file itself for hidden threats.

Some servers assign sequential ID numbers to files for internal database tracking.

Only open RAR files from trusted senders or known download portals.

If the file is part of a large multi-part archive, ensure you have the corresponding PAR (parity) files to verify data integrity and repair any corruption.

Since the origin of "23816.rar" is ambiguous, follow these security best practices if you have encountered this file:

In specific technical tests, numeric strings may represent file sizes; for example, "23816K" has been used to denote a specific compressed file size ( ) in Linux compression tests. Safety and Handling Recommendations

Could you provide on where you found this file or what you believe it contains? Knowing the website of origin or the file's size would help in identifying it. rar file problem.! - Adobe Community