: Right-click the file and select "Open archive" (do not extract yet). Look at the file names inside; they will tell you if it's a program, a collection of images, or a database.
The number "22101" might refer to (YYMMD format) or a specific internal build number for a software utility.
: It often contains textures, scripts, or map data for a specific version of a game mod.
Do you remember this file from or what software it was supposed to be for?