mydict = {'george': 16, 'amber': 19}
print mydict.keys()[mydict.values().index(16)] # Prints george
Or in Python 3.x:
mydict = {'george': 16, 'amber': 19}
print(list(mydict.keys())[list(mydict.values()).index(16)]) # Prints george
Basically, it separates the dictionary’s values in a list, finds the position of the value you have, and gets the key at that position.
More about keys() and .values() in Python 3: How can I get list of values from dict?