Numerical filenames are rarely random; they usually correspond to one of the following:
7-Zip / Discussion / Open Discussion: New RAR 5 format support
In enterprise environments, 22105 could be a specific record ID or a backup from a server taken on a certain date or sequence.
Below is a deep guide on understanding this file type, how to handle it safely, and common reasons why a file might be named with this specific number. 1. What is a .RAR File?