Prentiss is an unorganized territory in Penobscot County, Maine, United States. The township was named for Henry Prentiss, an early landowner. The population was 169 at the 2020 census. According to the United States Census Bureau, the unorganized territory has a total area of 38.4 square miles, of which 38.3 square miles is land and 0.04 square mil…Prentiss is an unorganized territory in Penobscot County, Maine, United States. The township was named for Henry Prentiss, an early landowner. The population was 169 at the 2020 census. According to the United States Census Bureau, the unorganized territory has a total area of 38.4 square miles, of which 38.3 square miles is land and 0.04 square miles, or 0.10%, is water.