Because this file comes from a "blog post" and is part of a large, segmented archive, ensure you trust the source. Segmented RAR archives are sometimes used to distribute large media files, software, or games, but they can also be used to hide malicious content.
To successfully extract the data inside, you typically need every single part in the series (e.g., part1, part2... through part21 and beyond). DODIFHV.part21.rar
Ensure you have downloaded all preceding parts (1 through 20) and any subsequent parts in the set into the same folder on your computer. Because this file comes from a "blog post"
When a file or folder is too large for a single download or storage device, it is often split into multiple "parts" or volumes. DODIFHV.part21.rar