Factor Calculator
Result
Factors: 1, 3, 7, 13, 21, 39, 91, 273, 487, 1461, 3409, 6331, 10227, 18993, 44317, 132951
Factor Pairs: (1, 132951) (3, 44317) (7, 18993) (13, 10227) (21, 6331) (39, 3409) (91, 1461) (273, 487)
Prime factors: 132951 = 3 × 7 × 13 × 487
132951  
  \  
44317  3  
  \  
6331  7  
  \  
487  13 
What is a factor?
In multiplication, factors are the integers that are multiplied together to find other integers. For example, 6 × 5 = 30. In this example, 6 and 5 are the factors of 30. 1, 2, 3, 10, 15, and 30 would also be factors of 30. Essentially, an integer a is a factor of another integer b, so long as b can be divided by a with no remainder. Factors are important when working with fractions, as well as when trying to find patterns within numbers.
Prime factorization involves finding the prime numbers that, when multiplied, return the number being addressed. For example, prime factorization of 120 results in 2 × 2 × 2 × 3 × 5. It can be helpful to use a factor tree when computing the prime factorizations of numbers. Using 120:
120
/ \
2 60
/ \
2 30
/ \
2 15
/ \
3 5

From the simple example of 120, it is clear that prime factorization can become quite tedious fairly quickly. Unfortunately, there is currently no known algorithm for prime factorization that is efficient for very large numbers. Many calculators, including the one on this page, cannot calculate prime factorizations beyond a certain magnitude. One concerted effort between several researchers to factor RSA768, a 232digit number, took 2 years using hundreds of machines.
Although no efficient algorithm has been found, it also has yet to be proven that no such algorithm exists, leaving room for anyone interested in having their name in a mathematical algorithm to formulate one (or prove in some selfnamed theorem that one doesn't exist)!