---
name: "factor"
section: "1plan9"
platform: "linux"
package: "9base"
version: "1:6-14"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/factor/1plan9"
---

# factor(1plan9)

factor a number, generate large primes

## NAME

factor, primes - factor a number, generate large primes

## SYNOPSIS

**factor** \[ *number* \]

**primes** \[ *start* \[ *finish* \] \]

## DESCRIPTION

*Factor* prints *number* and its prime factors, each repeated the proper number of times. The number must be positive and less than 2\*\*54 (about 1.8e16)

If no *number* is given, *factor* reads a stream of numbers from the standard input and factors them. It exits on any input not a positive integer. Maximum running time is proportional to sqrt(n).

*Primes* prints the prime numbers ranging from *start* to *finish*, where *start* and *finish* are positive numbers less than  2\*\*56. If  *finish* is missing, *primes* prints without end; if *start* is missing, it reads the starting number from the standard input.

## SOURCE

**/src/cmd/factor.c**\
 **/src/cmd/primes.c**