261

261 is an integer in the decimal number system. It is an odd, composite number that factors as 3 squared times 29, i.e., 261 = 3^2 × 29. Its position between 260 and 262 places it within the lower end of three-digit numbers.

In terms of divisors, 261 has six positive divisors: 1, 3, 9, 29, 87, and 261. It is divisible by 9, as the sum of its digits (2 + 6 + 1) equals 9. This makes 261 a Harshad number in base 10, meaning it is divisible by the sum of its digits. The prime factors are 3 and 29, with 3 appearing squared.

Representations of 261 in other bases include binary, octal, and hexadecimal. In binary, 261 is 100000101; in octal it is 405; and in hexadecimal it is 0x105. In Roman numerals, 261 is written as CCLXI.

Beyond pure mathematics, 261 has been used as a designation in various time and labeling systems. As a year, 261 CE would fall in the third century of the common era, and 261 BCE would appear in historical timelines for the pre-Common Era. In general reference works, 261 may also serve as a catalog, model, or code number in contexts where such numeric identifiers are employed, without implying a single universal meaning.