After extracting, verify the contents. Be wary of executable files like .exe or .bat hidden inside, as these are the primary way malware is delivered via archives.
In file sharing, large archives are often split into smaller "volumes." A file named 121.rar could be the 121st part of a massive multi-volume set. Safety and File Handling 121.rar
If you have encountered a file specifically named 121.rar from an unknown source: After extracting, verify the contents