<s>
On	O
Unix	B-Application
,	O
Plan	B-Operating_System
9	I-Operating_System
,	O
and	O
Unix-like	B-Operating_System
computer	O
systems	O
,	O
factor	O
is	O
a	O
utility	O
for	O
factoring	O
an	O
integer	O
into	O
its	O
prime	O
factors	O
.	O
</s>
<s>
factor	O
first	O
appeared	O
on	O
5th	B-Operating_System
edition	I-Operating_System
Research	B-Operating_System
Unix	I-Operating_System
in	O
1974	O
,	O
as	O
a	O
"	O
user	O
maintained	O
"	O
utility	O
(	O
section	O
6	O
of	O
the	O
manual	B-Protocol
)	O
.	O
</s>
<s>
In	O
the	O
7th	B-Operating_System
edition	I-Operating_System
in	O
1979	O
,	O
it	O
was	O
moved	O
into	O
the	O
main	O
"	O
commands	O
"	O
section	O
of	O
the	O
manual	B-Protocol
(	O
section	O
1	O
)	O
.	O
</s>
<s>
From	O
there	O
,	O
the	O
factor	O
utility	O
was	O
copied	O
to	O
all	O
other	O
variants	O
of	O
Unix	B-Application
,	O
including	O
commercial	B-Application
Unixes	B-Application
and	O
BSD	B-Operating_System
.	O
</s>
<s>
In	O
some	O
variants	O
of	O
Unix	B-Application
,	O
it	O
is	O
classified	O
as	O
a	O
"	O
game	O
"	O
more	O
than	O
a	O
serious	O
utility	O
,	O
and	O
therefore	O
documented	O
in	O
section	O
6	O
.	O
</s>
<s>
A	O
free	B-Application
software	I-Application
version	O
of	O
the	O
factor	O
utility	O
was	O
written	O
for	O
the	O
GNU	B-Operating_System
project	O
by	O
Paul	O
Rubin	O
,	O
in	O
1986	O
.	O
</s>
<s>
It	O
is	O
now	O
available	O
on	O
all	O
Linux	B-Application
distributions	O
as	O
part	O
of	O
the	O
GNU	B-Application
Core	I-Application
Utilities	I-Application
.	O
</s>
<s>
In	O
2008	O
,	O
GNU	B-Operating_System
factor	O
started	O
to	O
use	O
the	O
GNU	B-Application
MP	I-Application
library	O
for	O
arbitrary-precision	B-Algorithm
arithmetic	I-Algorithm
,	O
allowing	O
it	O
to	O
factor	O
integers	O
of	O
any	O
size	O
,	O
not	O
limited	O
by	O
the	O
machine	O
's	O
native	B-Language
datatypes	O
.	O
</s>
<s>
The	O
command	B-Application
is	O
available	O
as	O
a	O
separate	O
package	O
for	O
Microsoft	B-Application
Windows	I-Application
as	O
part	O
of	O
the	O
UnxUtils	B-Application
collection	O
of	O
native	B-Language
Win32	B-Library
ports	O
of	O
common	O
GNU	B-Operating_System
Unix-like	B-Operating_System
utilities	O
.	O
</s>
<s>
The	O
command	B-Application
can	O
be	O
used	O
by	O
supplying	O
an	O
integer	O
value	O
.	O
</s>
<s>
Various	O
projects	O
,	O
including	O
simple	O
ones	O
such	O
as	O
printing	O
prime	O
numbers	O
,	O
are	O
facilitated	O
by	O
using	O
this	O
command	B-Application
.	O
</s>
