This is documentation for Mathematica 5, 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. FactorInteger[m + I m] automatically works over the 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 Section 1.1.3, Section 1.4.9 and Section 3.2.4. Implementation Notes: see Section A.9.4. See also: IntegerExponent, Prime, PrimeQ, Divisors. Related package: NumberTheory`FactorIntegerECM`. New in Version 1; modified in 5.0.