Output code format of LTC2500-32's 32-bit no latency composite code mode

Hello

Now I want to use LTC2500-32 and LTC6363 to sample AC signal.And I use 32-bit no latency composite code mode which a 24-bit code representing the differential input voltage.I want to know which is the sign bit in the output data.In my code, the MCU can only output 32 bit , 16 bit or 8 bit signed number. What should I pay attention to if I want to output  negative voltage?

Thank you!