N
NumberPedia
Menu

© 2025 NumberPedia

Composite Number

51

51 is a odd composite number that follows 50 and precedes 52. It is composed of 4 distinct factors: 1, 3, 17, 51. Its prime factorization can be written as 3 × 17. 51 is classified as a deficient number based on the sum of its proper divisors. In computer science, 51 is represented as 110011 in binary and 33 in hexadecimal. Historically, it is written as LI in Roman numerals.

Roman Numeral
LI
LatinClassic
Binary
110011
Base 2
Hexadecimal
33
Base 16

Factor Analysis

4 Factors

Properties

ParityOdd
Perfect SquareNo
Perfect CubeNo
Digit Count2
Digit Sum6
Digital Root6
Sum of Factors72
Aliquot Sum21
ClassificationDeficient
Prime Factors2
SequencesComposite numbers, Deficient numbers
Prime Factorization

The prime factorization (3 × 17) reveals 2 prime building blocks.

Canonical form
3 × 17
317
Divisibility Insights
  • Divisible by 2

    51 ends in 1, so it is odd.

  • Divisible by 3

    The digit sum 6 is a multiple of 3.

  • Divisible by 4

    The last two digits 51 are not divisible by 4.

  • Divisible by 5

    51 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 6 is not a multiple of 9.

  • Divisible by 10

    51 does not end in 0.

  • Divisible by 11

    The alternating digit sum 4 is not a multiple of 11.

Sequence Membership

Deficient classification and digit analytics place 51 within several notable number theory sequences:

Composite numbersDeficient numbers
Advertisement

Deep dive

How 51 breaks down

51 carries 4 distinct factors and a digit signature of 6 (6 as the digital root). The deficient classification indicates that its proper divisors sum to 21, which stays below the number, offering a quick glimpse into its abundance profile.

Numeral conversions provide additional context: the binary form 110011 supports bitwise reasoning, hexadecimal 33 aligns with computing notation, and the Roman numeral LI keeps the encyclopedic tradition alive. These attributes make 51 useful for math olympiad problems, puzzle design, and code challenges alike.

Context

Where 51 shows up

Engineers lean on the divisibility profile when sizing circuits, mod designers use neighboring values (4656) to tune search ranges, and educators feature 51 in worksheets about factor trees. Its binary footprint of length 6 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 51 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 51

Is 51 a prime number?

51 is composite with 4 total factors and the prime factorization 3 × 17.

What is the prime factorization of 51?

It breaks down as 3 × 17, multiplying the primes 3 × 17.

How is 51 represented in binary and hexadecimal?

51 converts to 110011 in binary and 33 in hexadecimal, which are helpful for computer science applications.

Is 51 a perfect square, cube, or triangular number?

51 is not a perfect square, is not a perfect cube, and is not triangular.

What are the digit sum and digital root of 51?

The digits sum to 6, producing a digital root of 6. These tests power divisibility shortcuts for 3 and 9.