Home›Arithmetic dynamics›almost perfect number🌐EnglishEnglishBahasa IndonesiaDeutschEspañolFrançaisItalianoNederlandsSvenskaTiếng ViệtРусский中文日本語EntityQ1526045· pop 18· linked from 225 articlesalmost perfect numbernatural number whose proper divisors sum to one less than itselfAvailable in 18 languagesEspañolFrançais中文РусскийItalianoBahasa IndonesiaEsperantoFinnishHebrewHungarianConnectionsprime numberEntitydivisorEntityCategoriesArithmetic dynamicsDivisor functionInteger sequences