Is it possible to clock the RTC at a frequency higher than 32.768 kHz?
Yes. One would notice that all our specifications in the datasheet refer to the 32.768 kHz crystal. This is because all of our characterization tests have been conducted with a 32.768 kHz crystal and that is why the specs in the datasheet refer to it. But the RTC in itself has been designed to be clocked at a higher frequency. Hence, it is possible to run the RTC through an external clock running at a higher frequency - the maximum being 1 MHz.