How to open Part 21 of a multi-volume archive: Split or Compressed file .021 files
Have you had trouble opening the 021 file on your computer? What are 021 files? We explain what they are and recommend software that we know will open them.
What is 021 file?
A 021 file extension is related to split file or compressed file from a multi-volume archive (part 21).
Part 21 of a multi-volume archive: Split or Compressed file description
The 021 file extension is generally associated with split files. A part of larger file split using splitter software, such us HJSplit, WellTek 001 File Joiner & Splitter, SplitJoin or File Managers, such as Total Commander. It is also associated with several archivers or compression tools, which are using, or did use in the past, the 021 file extension for its multi-volume files or archives, such as Winrar (see part21.rar) or 7-Zip (see 7z.021).
In case of split files, you will need to merge them first with the use of the splitting/joining software tool, before you can open or work with them. If the files are compressed multi-volume archives, you will have to extract the first one and it will automatically continue to extract all the parts. In either case, you will need ALL the parts to access the original content.
Suggested software to open 021 file

7-zip
Popular open source file archiver with a high compression ratio

HJSplit
A freeware file-splitting software
Split File Shell Extension
A file spliting utility

Total Commander
Highly popular file manager for Windows
There are other 021 filename extensions with the same .021 suffix
021 - Winfunktion Mathematic v8.0 Julia fractal: File format for Julia fractals in Winfunktion Mathematic version 8.0
A 021 file extension is related to the Winfunktion Mathematic and used for its Julia fractal files.