# Manual browser: factor(6)

FACTOR(6) | Games Manual | FACTOR(6) |

# NAME

**factor**— factor a number

# SYNOPSIS

factor |
[number ...] |

# DESCRIPTION

The**factor**utility factors integers larger than 1. When a number is factored, it is printed, followed by a “:”, and the list of (prime) factors on a single line. Factors are listed in ascending order, and are preceded by a space. If a factor divides a value more than once, it will be printed more than once.

When **factor** is invoked with one or more arguments, each argument will be factored.

When **factor** is invoked with no arguments, **factor** reads numbers, one per line, from standard input, until end of file or error. Leading white-space and empty lines are ignored. Numbers may be preceded by a single +. Integer less than 2 are rejected. Numbers are terminated by a non-digit character (such as a newline). After a number is read, it is factored. Input lines must not be longer than LINE_MAX - 1 (currently 2047) characters.

By default, **factor** is compiled against the OpenSSL bignum implementation openssl_bn(3), which lets it handle arbitrarily large values. (Note however that very large values can take a very long time to factor.) If **factor** is compiled without OpenSSL it is limited to the maximum value of unsigned long.

# DIAGNOSTICS

Out of range or invalid input results in an appropriate error message to standard error.# AUTHORS

Originally by .May 15, 2010 | NetBSD 7.0 |