261 (number)

261 (two hundred [and] sixty-one) is the natural number following 260 and preceding 262. It has the prime factorization 32·29.

Mathematical properties
There are six divisors of this number, the divisors being, , , , , and 261 itself. 261 is a deficient number, since $1 + 3 + 9 + 29 + 87 = 129 < 261.$

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 $100000101_{2}$ (with 3 ones in it).