Rabbi Moshe Shapiro (1935-2017) explains that all words derived from the SAMECH-PEH-REISH root are interrelated. He explains that sippur denotes joining together multiple details to form a singular, holistic unit—the “story”. This resembles a sefer (book), which includes all the details and contents recorded therein, and binds them together into one entity. Similarly, a sfar (border) confines everything within its boundary and makes them into one unit — whether it is the border of a country or the city limits. Finally, mispar (number) and sofer (counting) refer to the system of counting numbers that are all bound together in an organized and logical way.
If all such roots are related, how does להסתפר fit in?