A 6-round competition conducted over the internet has 1,000,000 competitors participating in the first round. At the end of each round, 1/5 of the competitors who participated in that round are eliminated, and only the remaining competitors in their entirety participate in the next round.
Accordingly, how many competitors remain at the end of the 6th round?
A) $2^{16}$
B) $2^{18}$
C) $2^{20}$
D) $2^{22}$
E) $2^{24}$