factor, primes - factor a number, generate large primes

Factor prints number and its prime factors, each repeated the proper number of times.  The number must be
       positive and less than 2**54 (about 1.8e16)

       If  no  number  is  given, factor reads a stream of numbers from the standard input and factors them.  It
       exits on any input not a positive integer.  Maximum running time is proportional to sqrt(n).

       Primes prints the prime numbers ranging from start to finish, where start and finish are positive numbers
       less than 2**56.  If finish is missing, primes prints without end; if start  is  missing,  it  reads  the
       starting number from the standard input.

       factor, primes - factor a number, generate large primes

/src/cmd/factor.c/src/cmd/primes.cFACTOR(1plan9)

factor [ number ]

       primes [ start [ finish ] ]