687
687 is a odd composite number that follows 686 and precedes 688. It is composed of 4 distinct factors: 1, 3, 229, 687. Its prime factorization can be written as 3 × 229. 687 is classified as a deficient number based on the sum of its proper divisors. In computer science, 687 is represented as 1010101111 in binary and 2AF in hexadecimal. Historically, it is written as DCLXXXVII in Roman numerals.
Factor Analysis
4 FactorsProperties
The prime factorization (3 × 229) reveals 2 prime building blocks.
Divisible by 2
687 ends in 7, so it is odd.
Divisible by 3
The digit sum 21 is a multiple of 3.
Divisible by 4
The last two digits 87 are not divisible by 4.
Divisible by 5
687 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 21 is not a multiple of 9.
Divisible by 10
687 does not end in 0.
Divisible by 11
The alternating digit sum 5 is not a multiple of 11.
Deficient classification and digit analytics place 687 within several notable number theory sequences:
Timeline
Deep dive
How 687 breaks down
687 carries 4 distinct factors and a digit signature of 21 (3 as the digital root). The deficient classification indicates that its proper divisors sum to 233, which stays below the number, offering a quick glimpse into its abundance profile.
Numeral conversions provide additional context: the binary form 1010101111 supports bitwise reasoning, hexadecimal 2AF aligns with computing notation, and the Roman numeral DCLXXXVII keeps the encyclopedic tradition alive. These attributes make 687 useful for math olympiad problems, puzzle design, and code challenges alike.
Context
Where 687 shows up
Engineers lean on the divisibility profile when sizing circuits, mod designers use neighboring values (682–692) to tune search ranges, and educators feature 687 in worksheets about factor trees. Its binary footprint of length 10 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 687 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 687
Is 687 a prime number?
687 is composite with 4 total factors and the prime factorization 3 × 229.
What is the prime factorization of 687?
It breaks down as 3 × 229, multiplying the primes 3 × 229.
How is 687 represented in binary and hexadecimal?
687 converts to 1010101111 in binary and 2AF in hexadecimal, which are helpful for computer science applications.
Is 687 a perfect square, cube, or triangular number?
687 is not a perfect square, is not a perfect cube, and is not triangular.
What are the digit sum and digital root of 687?
The digits sum to 21, producing a digital root of 3. These tests power divisibility shortcuts for 3 and 9.