1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Number and sum of prime factors of a number

  1. Mar 22, 2013 #1
    Given a large number N, do we have any formula to find the number of prime factors and their sum like τ(N) and σ(N) functions?

    CONDITION: One should not list the factors of N or is not allowed to factorize N since afterwards it would be just a matter of counting and addition
  2. jcsd
  3. Mar 22, 2013 #2
    If such a formula ## f(N) ## exists, what would ## f(N) = 1 ## mean?
  4. Mar 22, 2013 #3
    I believe if such a formula does exist then the entire internet would be vulnerable. The internet is secure because of prime number factorisation. See RSA Algorithm

    There is a formula to find if a number is prime or not, but not the factors.

  5. Mar 22, 2013 #4
    That actually looks like a "formula" to find the ## n ##th prime, but such "formulas" are really just symbolic descriptions of (very ineffecient) algorithms and of no practical importance.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook