Sure there is integer Math. But you can produce Frequency using the PCA engine in X2 mode @ 20MHz in Highspeed mode (see intel app note mentioned many times in this forum):

increment of 250+250 gives symmetric 20000Hz
increment of 250+251 gives asymmetric 19960Hz
increment of 250+249 gives asymmetric 20040Hz
increment of 249+249 gives symmetric 20080Hz

the integer math is done in 100nsec quantas

Werner