Blue pill: What is my sampling frequency ?

Hello,

My adc clock is 140.625 KHz

My sample time is 239.5 Cycles

So my Conversion time = 239.5 Cycles + 12.5 Cycles = 251.5 Cycles.

1 Cycle = 1/Adc Clock 1/140.625 KHz = 7.1uS

So total conversion time = 251.5 * 7.1uS = 1.78ms

i.e my sampling frequency = 1/Conversion time = 559 Hz

Is my calculation correct ?