Here is one detailed explanation on how the 133,000,000 figure was incorrectly arrived at. I chose a foreign source, figuring that most US sources would be strongly biased for one party or the other.
https://www.reuters.com/article/uk-factcheck-voters-133-million/fact-check-133-million-registered-voters-argument-uses-flawed-logic-idUSKBN296284
Reuters = Fake News