# Wolfram Language & System 10.0 (2014)|Legacy Documentation

This is documentation for an earlier version of the Wolfram Language.
BUILT-IN WOLFRAM LANGUAGE SYMBOL

# FactorInteger

gives a list of the prime factors of the integer n, together with their exponents.

FactorInteger[n,k]
does partial factorization, pulling out at most k distinct factors.

## Details and OptionsDetails and Options

• For negative numbers, the unit is included in the list of factors.
• FactorInteger also works on rational numbers. The prime factors of the denominator are given with negative exponents. »
• The last element in the list FactorInteger[n,k] gives what is left after the partial factorization.
• factors over Gaussian integers. »
• FactorInteger[m+I n] automatically works over the Gaussian integers.
• When necessary, a unit of the form , {I,1}, or {-I,1} is included in the list of factors.
• pulls out only factors that are easy to find.
• FactorInteger uses PrimeQ to determine whether factors are prime.

## ExamplesExamplesopen allclose all

### Basic Examples  (2)Basic Examples  (2)

Find prime factors and their exponents:

 Out[1]=
 Out[1]=