string => number

encode_word.py

def encode(text, decode=False):
    "Credit for this strategy goes to http://stackoverflow.com/a/16872684"  
    table = {'a':2, 'b':3, 'c':5, 'd':7, 'e':11, 'f':13, 'g':17, 'h':19, 
    'i':23, 'j':29, 'k':31, 'l':37, 'm':41, 'n':43,'o':47, 'p':53, 'q':59, 
    'r':61, 's':67, 't':71, 'u':73, 'v':79, 'w':83, 'x':89, 'y':97, 'z':101}  
    if not decode: 
        return reduce(mul,[table[char] for char in text]) if text else ''