This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 FactorInteger FactorInteger[ n ] gives a list of the prime factors of the integer n, together with their exponents. Example: FactorInteger[2434500]. For negative numbers, the unit {-1, 1} is included in the list of factors. FactorInteger also works on rational numbers. The prime factors of the denominator are given with negative exponents. FactorInteger[ n , GaussianIntegers->True] factors over Gaussian integers. When necessary, a unit of the form {-1, 1}, {I, 1} or {-I, 1} is included in the list of factors. FactorInteger[ n , FactorComplete->False] does fast but not necessarily complete factorization, and extracts only factors that are easy to find. See the Mathematica book: Section 1.1.3, Section 1.4.8, Section 3.2.4. See also Implementation NotesA.9.44.7MainBookLinkOldButtonDataA.9.44.7. See also: Prime, PrimeQ, Divisors. Related package: NumberTheory`FactorIntegerECM`. Further Examples Here is the prime factorization of a 9-digit number. In[1]:= Out[1]= The number is not a prime for for . In[2]:= Out[2]= A prime over the integers may factor in the Gaussian integers. In[3]:= Out[3]=