On page 24 of the datasheet they describe the notch filter shown in figure 23.
It says:
"This circuit yields a notch with about 40 dB of attenuation
at 60 Hz. A notch is formed by subtracting the bandpass
output of a mode 3 configuration from the input using the unused
side B opamp. The Q is 10 and the gain is 1 V/V in the
passband. However, fCLK/f0 = 1000 to allow for a wide input
spectrum. This means that for pin 12 tied to ground (100:1
mode), R4/R2 = 100. The offset voltage at the lowpass output
(LP) will be about 3V. However, this is an extreme case
and the resistor ratio is usually much smaller."