Modern RAR files (version 5.0 and later) utilize a 56-bit BLAKE2sp hash for better integrity checking compared to the older 32-bit CRC32.
If you did not expect a file named 56905.rar or found it in a suspicious location, exercise extreme caution. How to Open RAR Files on Windows, Mac, and Mobile - Avast 56905.rar
Users may use date stamps or sequential numbering for private archiving. Security Warning Modern RAR files (version 5