factor writes to standard input all prime factors for any positive integer less than or equal to 10^14. The prime factors are written the proper number of times.
If factor is used without an argument, it waits for an integer to be entered. After entry of the integer, it factors it, writes its prime factors the proper number of times, and then waits for another integer. factor exits if a 0 or any non-numeric character is entered.
If factor is invoked with an argument (integer), it writes the integer, factors it and writes all the prime factors as described above, and then exits. If the argument is 0 or non-numeric, factor writes a 0 and then exits.
The maximum time to factor an integer is proportional to sqrt(n), where n is the integer which is entered. factor will take this time when n is prime or the square of a prime.
See attributes(5) for descriptions of the following attributes: