Английская Википедия:261 (number)
Материал из Онлайн справочника
Шаблон:Infobox number 261 (two hundred [and] sixty-one) is a natural number proceeded by the number 260 and followed by 262. It has the prime factorization 32·29.
Mathematical properties
There are six divisors of this number, the divisors being Шаблон:Num, Шаблон:Num, Шаблон:Num, Шаблон:Num, Шаблон:Num, and 261 itself.[1] 261 is a deficient number, since Шаблон:Math
261 is nonagonal number, unique period in base 2, and the number of possible unfolded tesseract patterns.
261 is a lucky number, as well as an odious number, meaning it has an odd number of 1's in its binary expansion, which is Шаблон:Math (with 3 ones in it).[2]
References