261 (number)
# 261 (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 $3^2·29.$

## Mathematical properties

There are six divisors of this number, the divisors being 1, 3, 9, 29, 87, 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).

