19
down vote
The number 32768 is a power of 2, i.e. it is 2^15. If you have a 32.768kHz clock frequency it is easy to divide it to an 1Hz frequency using binary frequency dividers, a.k.a. binary counters, i.e. chains of flip-flops.
Having a 1Hz frequency means you have a clock signal which provides 1s time resolution: count the seconds with a counter, do the math and you have a Real-Time Clock (RTC)