EntityQ18206266· pop 14· linked from 19 articlesEuclid–Euler theoremSign in to savetheorem characterizing the even perfect numbersConnectionsEuclidEntityLeonhard EulerEntityInternational Standard Book NumberEntitynatural numberEntityprime numberEntitynumber theoryEntitydigital object identifierEntityIbn al-HaythamEntitytheoremEntitygolden ratioEntityirrational numberEntityElementsEntityparityEntityperfect numberEntitydivisorEntityJSTOREntityUniversity of St AndrewsEntityQ118398EntityMersenne primeEntitycoprimeEntityCategoriesEuclidLeonhard EulerMersenne primesPerfect numbersTheorems in number theory