You can call the digits to the left of the decimal point integer digits or integral digits and those to the right of the decimal point fraction digits or fractional digits.
Java I/O, Harold (2006):
For instance, in the number 31.415, there are two integer digits and three fraction digits.
Microprocessor Engineering, Holdsworth (2013):
...where n is the number of integral digits and m the number of fractional digits.
Perhaps these terms are not well-established, but they are used in the literature and will be understood in the appropriate context.