Find all numbers between 2 and 100 co-prime to a given number
CJam, 23 bytes

101,:N2&gt;q~mf{N%-}/", "*


Try it online. Paste the Code, type an integer in Input and click Run.

Example

$ cjam factor.cjam &lt;&lt;&lt; 210
11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97


How it works

101,:N # Push the array [ 0 ... 100 ] and save it in “N”.
2&gt;     # Remove 0 and 1 from the array.
q~mf   # Read from STDIN, interpret the input and factorize the resulting integer.
{      # For each prime factor:
  N%   # Collect all multiples of the prime factor in an array.
  -    # Apply set difference with the array on the stack.
}/     # This leaves only integers that are coprime with the input.
", "*  # Join by commas and spaces.