factor is used to list all prime factors of each integer number.

$ factor [NUMBER]...

will list every prime factor the the list of input numbers. The other main usage for factor,

$ factor

with no command line arguments, input will be read from standard input.

Generally, use:

$ factor [NUMBER1] [NUMBER2]...

Useful Options / Examples

There are very few options for factor. there are only two.

$ factor --help

will display a help file and exit.

$ factor --versions

will display version information and exit.