calculating red LED resistor arduino
Forward voltage of the LED specified in the question is typically 2.2 volts at 20 mA so, from a 5V supply the resistor will drop typically 2.8 volts and, with 20 mA flowing it should have a resistance of 140 ohms.

If the forward volt drop of the LED were at the lowest value specified i.e. 1.9 volts then a 140 ohm resistor would permit a current of 22 mA and that would be fine (less than the maximum continuous forward current of 30 mA).