It's a myth that you need at least 61% to pass the PMP® Exam.
Well, this might have been partially true till 2005 but not anymore.
There is no fixed score to clear the PMP® exam.
The marks you obtain will be based on the difficulty level of the questions you get. PMI follows such a format because the PMP® certification exam is a psychometric test.
In this, no two candidates get the same set of questions nor all the questions carry equal weightage. If you get a questionnaire with easy questions, then the passing score is likely to be higher for you. Similarly, if you get difficult questions, then the passing score will be much lower.