@jblowsmoke @elonmusk yes, yes it is true
if a  is flipped 21 times, the probability of 21 heads is 1 in 2,097,152. the probability of flipping a head after having already flipped 20 heads in a row is 
 assuming a :
the probability of 20 heads, then 1 tail is 0.520 × 0.5 = 0.521