121
121 is a odd composite number that follows 120 and precedes 122. It is composed of 3 distinct factors: 1, 11, 121. Its prime factorization can be written as 11^2. 121 is classified as a deficient number based on the sum of its proper divisors. In computer science, 121 is represented as 1111001 in binary and 79 in hexadecimal. Historically, it is written as CXXI in Roman numerals. It also belongs to the perfect square sequence.
Factor Analysis
3 FactorsProperties
The prime factorization (11^2) reveals 2 prime building blocks.
Divisible by 2
121 ends in 1, so it is odd.
Divisible by 3
The digit sum 4 is not a multiple of 3.
Divisible by 4
The last two digits 21 are not divisible by 4.
Divisible by 5
121 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 4 is not a multiple of 9.
Divisible by 10
121 does not end in 0.
Divisible by 11
The alternating digit sum 0 is a multiple of 11.
Deficient classification and digit analytics place 121 within several notable number theory sequences:
Timeline
Deep dive
How 121 breaks down
121 carries 3 distinct factors and a digit signature of 4 (4 as the digital root). The deficient classification indicates that its proper divisors sum to 12, which stays below the number, offering a quick glimpse into its abundance profile.
Numeral conversions provide additional context: the binary form 1111001 supports bitwise reasoning, hexadecimal 79 aligns with computing notation, and the Roman numeral CXXI keeps the encyclopedic tradition alive. These attributes make 121 useful for math olympiad problems, puzzle design, and code challenges alike.
Context
Where 121 shows up
Engineers lean on the divisibility profile when sizing circuits, mod designers use neighboring values (116–126) to tune search ranges, and educators feature 121 in worksheets about factor trees. Its binary footprint of length 7 bits also makes it a solid example for teaching storage limits and overflow.
Beyond STEM, the classification and sequence tags (Composite numbers, Deficient numbers, Perfect squares) help historians, numerologists, and trivia writers tie 121 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 121
Is 121 a prime number?
121 is composite with 3 total factors and the prime factorization 11^2.
What is the prime factorization of 121?
It breaks down as 11^2, multiplying the primes 11 × 11.
How is 121 represented in binary and hexadecimal?
121 converts to 1111001 in binary and 79 in hexadecimal, which are helpful for computer science applications.
Is 121 a perfect square, cube, or triangular number?
121 is a perfect square, is not a perfect cube, and is not triangular.
What are the digit sum and digital root of 121?
The digits sum to 4, producing a digital root of 4. These tests power divisibility shortcuts for 3 and 9.