Often, the cause of a high view count is that the question was featured in the "Hot Network Questions". However, this is usually coupled with a considerable amount of votes and comments. That is not the case here.
Moreover, the HNQ formula itself selects questions with high scores (scores of answers also count) so it's therefore quite unlikely that this question would have even entered the HNQ with such low scores.
I've checked The Wayback Machine, and there's no trace of the question in the HNQ for a relevant time period., 
So I think we can safely rule out that the HNQ played a significant part in this view count. There may be a slim theoretical chance, but it seems so extremely unlikely that it borders on the impossible.
The fact that hardly any of the 18k viewers voted on the question/answers indicates strongly to me that they mostly did not have accounts or reputation on Stack Exchange. This leads me to suspect that they were visitors coming through search engines.
It's generally also sometimes the case that a question can be linked to on a popular blog or website. That also tends to produce a lot of views without votes. However, this doesn't seem to be the case here. I tried googling the link to your question and I didn't find any relevant results. I guess it's possible, but I have found no evidence of it.