+148 Because when you divide 13 by two, you have 6 remainder 1
The definition of an even number is that it can be divided by two without leaving a remainder
+118724 Mmm some numbers are just sad and lonely.
As TM just pointed our, 13 can never be paired off. 
13 is a loner, he can never work in any groups.
He is like an octopus.
Did you know that the octopus is an extremely intelligent creature and it is very capbale of learning by copying another of its species. BUT in nature they live solitary lives so they never learn from one another and hence they can never advance.
Perhaps advancement is not that important. If an octopus feels emotion, perhaps it is happy, I do not know. But I do know that in some respects it can be compared to our prime number 13.
+118724 Maybe I touched a blue ring octopus. They are very pretty and invite inquisitive fingers but if I had done that I would not be here to tell the tale. So perhaps, as you say, it was a spider whose poisonous fangs did inject me. ://
https://gyazo.com/dadbe177fd7245c329c0d49ec6ee5237
òwhy is 13 not even
