To find the files older than 17 days:

$ find . -daystart -mtime +17 -print

The reason to use `-daystart` is to make things more natural for human beings, because `find` performs some rounding; from the man page:

When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago.

To find files that were accessed exactly 17 days ago (that is: that have been accessed between 00:00 and 23:59:59 on the day that was 17 days ago):

$ find . -daystart -mtime 17 -print

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