5. Given the first seven digits of an 11-digit mobile phone number are 1390931. If the remaining four digits can only be 1, 3, 5 and each must appear at least once, then there are such mobile phone numbers.

 untranslated: 个. 

Note: The word "个" at the end of the sentence is not translated as it is a placeholder for the answer.
5. 36 .