The ratio of yes votes to no votes is 4 to 7, which can be simplified to 2 to 7/2 or 2:3.5. This means that for every 3.5 no votes, there are 2 yes votes. Since there were 3794 no votes, there were 3794/3.5 = <<3794/3.5=1082>>1082 sets of yes and no votes.
The total number of votes is therefore 21082 + 3794 = <<21082+3794=6858>>6858 votes.