Identify the MOST SPECIFIC set to which each of the following numbers belongs.

47
144
-9
0.121212...
0
Rational number
Integer
Natural number
Whole number
Irrational number

47: Natural number, Integer, Rational number

144: Natural number, Integer, Rational number
-9: Integer, Rational number
0.121212...: Irrational number
0: Whole number, Integer, Rational number