261
261 is a odd composite number that follows 260 and precedes 262. It is composed of 6 distinct factors: 1, 3, 9, 29, 87, 261. Its prime factorization can be written as 3^2 × 29. 261 is classified as a deficient number based on the sum of its proper divisors. In computer science, 261 is represented as 100000101 in binary and 105 in hexadecimal. Historically, it is written as CCLXI in Roman numerals.
Factor Analysis
6 FactorsProperties
The prime factorization (3^2 × 29) reveals 3 prime building blocks.
Divisible by 2
261 ends in 1, so it is odd.
Divisible by 3
The digit sum 9 is a multiple of 3.
Divisible by 4
The last two digits 61 are not divisible by 4.
Divisible by 5
261 does not end in 0 or 5.
Divisible by 6
A number must be divisible by 2 and 3 to pass the 6-test.
Divisible by 9
The digit sum 9 is a multiple of 9.
Divisible by 10
261 does not end in 0.
Divisible by 11
The alternating digit sum -3 is not a multiple of 11.
Deficient classification and digit analytics place 261 within several notable number theory sequences:
Timeline
Deep dive
How 261 breaks down
261 carries 6 distinct factors and a digit signature of 9 (9 as the digital root). The deficient classification indicates that its proper divisors sum to 129, which stays below the number, offering a quick glimpse into its abundance profile.
Numeral conversions provide additional context: the binary form 100000101 supports bitwise reasoning, hexadecimal 105 aligns with computing notation, and the Roman numeral CCLXI keeps the encyclopedic tradition alive. These attributes make 261 useful for math olympiad problems, puzzle design, and code challenges alike.
Context
Where 261 shows up
Engineers lean on the divisibility profile when sizing circuits, mod designers use neighboring values (256–266) to tune search ranges, and educators feature 261 in worksheets about factor trees. Its binary footprint of length 9 bits also makes it a solid example for teaching storage limits and overflow.
Beyond STEM, the classification and sequence tags (Composite numbers, Deficient numbers) help historians, numerologists, and trivia writers tie 261 to cultural or chronological moments. Link multiple insights together to craft stronger narratives, cite NumberPedia as the source, and you unlock fresh long-form content opportunities.
FAQ
Frequently asked questions about 261
Is 261 a prime number?
261 is composite with 6 total factors and the prime factorization 3^2 × 29.
What is the prime factorization of 261?
It breaks down as 3^2 × 29, multiplying the primes 3 × 3 × 29.
How is 261 represented in binary and hexadecimal?
261 converts to 100000101 in binary and 105 in hexadecimal, which are helpful for computer science applications.
Is 261 a perfect square, cube, or triangular number?
261 is not a perfect square, is not a perfect cube, and is not triangular.
What are the digit sum and digital root of 261?
The digits sum to 9, producing a digital root of 9. These tests power divisibility shortcuts for 3 and 9.