What have 527, 538 and 270 to do with the US Presidential election?

Many thanks to all those who took part in my quick quiz. Most people got the right answer, but quite a few got wrong answers.

Here's the full SP. The question was: Which of the following has nothing to do with the US Presidential election?

The correct answer was 519, which was a random number I thought of, and then checked on Google to confirm it had nothing to do with the election. (Although you could argue that if a Presidential candidate won all the states except Arizona and Louisiana, they would have 519 college votes. But it's rather unlikely.)

The other potential answers were:

527 - "A 527 group is a type of American tax-exempt organization named after a section of the United States tax code, 26 U.S.C. § 527. A 527 group is created primarily to influence the nomination, election, appointment or defeat of candidates for public office." - Wikipedia

538 - is the total electoral college votes up for grabs in the US Presidential election.

270 - is the number of electoral college votes that a candidate needs to win the election.

Again - many thanks for your participation.