title: Cannot convert 16 digit number to human readable date
body: <p>I have read a large csv file into a Jupyter notebook, and it contains a column of 16 digit numbers (e.g. 1352160000000000) as an Epoch/Unix timestamp. </p>
  
  <p>I have checked this number on an online Epoch/Unix timestamp converter site and it returns the time I know it should (GMT: Tuesday, November 6, 2012 12:00:00 AM). </p>
  
  <p>I then used the following code (adapted from other answers to this question on this site): <code>df['TIME'] = pd.to_datetime(df['TIME'], unit='u')</code> to convert this number to human readable form in my data frame but I either get an error, or I get (1970-01-16 15:36:00.000).  </p>
  
  <p>Can anyone point out to me where it is I am going wrong, and what I am missing?</p>