second largest known prime number, and the second largest known perfect number, after and , proved prime and perfect by Édouard Lucas seven years earlier. They remained the second largest until 1911, when Ralph Ernest Powers proved that is prime and is perfect. Pervushin was a contributor to the International World Congress of Mathematicians of 1893, a part of the World's Columbian Exposition in Chicago that became a precursor to the later International Congresses of Mathematicians. However, he did not attend. References Russian mathematicians 1827 births 1900 deaths Russian Christians Burials in Kurgan Oblast