What is the average Election, when % Of Prefectural Vote is 38.57%, and when # Of Prefectural Votes is greater than 21,114,727?
CREATE TABLE "councillors_election_results" (
  "election" real,
  "leader" text,
  "num_of_seats_won" real,
  "num_of_national_votes" real,
  "pct_of_national_vote" text,
  "num_of_prefectural_votes" real,
  "pct_of_prefectural_vote" text
);
SELECT AVG("election") FROM "councillors_election_results" WHERE "pct_of_prefectural_vote"='38.57%' AND "num_of_prefectural_votes">'21,114,727';