Promethium-147 is a radioactive isotope of the element promethium, which is part of the lanthanide series in the periodic table. It has a half-life of about 2.62 days, meaning it takes this amount of time for half of a sample to decay. This isotope is primarily produced in nuclear reactors and is not found in significant amounts in nature. Due to its radioactive properties, Promethium-147 is used in various applications, including luminous paint for watch dials and instrument panels, as well as in nuclear batteries for powering small devices. Its ability to emit beta particles makes it useful in certain types of scientific research and industrial applications.