How many congressmen are there in the House? A vote said 404-0, 27 not voting, but where are the other 4?

Question

That accounts for 431. Where are the other 4?

Some of the 27 were not present in the House.

Are there any vacancies in the House?

Answer 1

There are 435 voting members of Congress. On a particular vote, all 435 might not be accounted for. Some are absent for various reasons. Many (most) who choose to miss a vote have a good reason, but rarely if the vote is important and passage will depend on their one vote.

If it's really an important vote, they will literally fly in from all over the world to make sure their vote is counted. If it's something really mundane like approving the minutes of the previous day, there could be over a hundred members absent for the day.

Frankly, if I were you, I wouldn't worry about it. The public's business does not depend on every member of Congress being present for each and every vote.

Answer 2

There are 435 Members of the House of Representatives. A few vacant seats might exist, since I know of at least one member who died recently and his replacement has not yet been named by the Governor of his state. In addition, there are members who either vote "Present" or are absent for the vote.
The link below will give you the vote by member and you can check to see who didn't cast a vote. BTW, I believe the vote you cited was for a bill concerned with WiFi. There were two votes against it: Ron Paul of Texas and a Congressman from Georgia.

Answer 3

They might not have been in attendance. The vote count is those who were there, whether they voted or abstained.