The provided source material does not contain information regarding a city named Yefremov. Instead, it identifies Yefremov (or Efremov) as a common Russian surname derived from the male given name Yefrem, which is the Russian form of the Hebrew name Ephraim.
The name literally means "Yefrem's" and originates from the Hebrew term for "fruitful, fertile and productive." The source lists various notable individuals with this surname, including Soviet politicians, athletes, actors, and scientists.