title: Convert pandas series cell to string and datetime object
body: <p>I have sliced the pandas dataframe.</p>
  
  <pre><code>end_date = df[-1:]['end'] 
  
  type(end_date) 
  Out[4]: pandas.core.series.Series 
  
  end_date 
  Out[3]: 
  48173   2017-09-20 04:47:59 
  Name: end, dtype: datetime64[ns] 
  </code></pre>
  
  <ol>
  <li>How to get rid of end_date's index value <code>48173</code> and get only <code>2017-09-20 04:47:59</code> string? I have to call REST API with <code>2017-09-20 04:47:59</code> as a parameter, so I have to get string from pandas <code>datetime64</code> series. </li>
  <li>How to get rid of end_date's index value <code>48173</code> and get only datetime object [something like <code>datetime.datetime.strptime('2017-09-20 04:47:59', '%Y-%m-%d %H:%M:%S')</code>]. I need it because, later I will have to check if <code>'2017-09-20 04:47:59' &lt; datetime.datetime(2017,1,9)</code> </li>
  </ol>
  
  <p>I need to convert just a single cell value, not a whole column.
  How to do these conversions?</p>