v7 man page for factor

FACTOR(1)						      General Commands Manual							 FACTOR(1)

NAME
       factor, primes - factor a number, generate large primes

SYNOPSIS
       factor [ number ]

       primes

DESCRIPTION
       When  factor  is  invoked without an argument, it waits for a number to be typed in.  If you type in a positive number less than 256 (about
       7.2e16) it will factor the number and print its prime factors; each one is printed the proper number of times.  Then it waits  for  another
       number.	It exits if it encounters a zero or any non-numeric character.

       If factor is invoked with an argument, it factors the number as above and then exits.

       Maximum time to factor is proportional to sqrt(n) and occurs when n is prime or the square of a prime.  It takes 1 minute to factor a prime
       near 1014 on a PDP11.

       When primes is invoked, it waits for a number to be typed in.  If you type in a positive number less than 256  it  will	print  all  primes
       greater than or equal to this number.

DIAGNOSTICS
       `Ouch.' for input out of range or for garbage input.

																	 FACTOR(1)