191
191 is a odd prime number that follows 190 and precedes 192. As a prime number, 191 is only divisible by 1 and itself. It holds a unique position in the sequence of integers. Its prime factorization is simply 191. 191 is classified as a deficient number based on the sum of its proper divisors. In computer science, 191 is represented as 10111111 in binary and BF in hexadecimal. Historically, it is written as CXCI in Roman numerals.
Factor Analysis
2 FactorsProperties
191 is prime, so its only factors are 1 and 191.
Divisible by 2
191 ends in 1, so it is odd.
Divisible by 3
The digit sum 11 is not a multiple of 3.
Divisible by 4
The last two digits 91 are not divisible by 4.
Divisible by 5
191 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 11 is not a multiple of 9.
Divisible by 10
191 does not end in 0.
Divisible by 11
The alternating digit sum -7 is not a multiple of 11.
Deficient classification and digit analytics place 191 within several notable number theory sequences:
Timeline
Deep dive
How 191 breaks down
191 carries 2 distinct factors and a digit signature of 11 (2 as the digital root). The deficient classification indicates that its proper divisors sum to 1, which stays below the number, offering a quick glimpse into its abundance profile.
Numeral conversions provide additional context: the binary form 10111111 supports bitwise reasoning, hexadecimal BF aligns with computing notation, and the Roman numeral CXCI keeps the encyclopedic tradition alive. These attributes make 191 useful for math olympiad problems, puzzle design, and code challenges alike.
Context
Where 191 shows up
Engineers lean on the divisibility profile when sizing circuits, mod designers use neighboring values (186–196) to tune search ranges, and educators feature 191 in worksheets about prime identification. Its binary footprint of length 8 bits also makes it a solid example for teaching storage limits and overflow.
Beyond STEM, the classification and sequence tags (Prime numbers, Deficient numbers) help historians, numerologists, and trivia writers tie 191 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 191
Is 191 a prime number?
191 is prime, meaning it is only divisible by 1 and itself.
What is the prime factorization of 191?
191 is already prime, so the factorization is simply 191.
How is 191 represented in binary and hexadecimal?
191 converts to 10111111 in binary and BF in hexadecimal, which are helpful for computer science applications.
Is 191 a perfect square, cube, or triangular number?
191 is not a perfect square, is not a perfect cube, and is not triangular.
What are the digit sum and digital root of 191?
The digits sum to 11, producing a digital root of 2. These tests power divisibility shortcuts for 3 and 9.