Does 3x22μF mean three capacitors of 22μF in parallel or series?
They are in parallel as mentioned in the datasheet in order to obtain a largish capacitance with SMD parts:


  For the output capacitor, use of a small ceramic capacitor placed as close as possible to the VOUT and PGND
  pins of the device is recommended. If, for any reason, the application requires the use of large capacitors which
  can not be placed close to the device, use a smaller ceramic capacitor in parallel to the large capacitor. The
  small capacitor should be placed as close as possible to the VOUT and PGND pins of the device. The
  recommended typical output capacitor value is 66 µF with a variance as outlined in Table 1.


(Emphasis mine.)

As for the input


  To improve transient behavior of the regulator and EMI behavior of the total power supply circuit, this design suggests a minimum input capacitance of 20 μF.


Honestly, I'm not sure why you'd want two 10μF caps there instead of just one 22μF if you're going to BOM those for the output anyway. If you're doing this for production, you'd have take out your calculator and add parts costs to insertion costs and consider the trade-off in board space etc.