In the Ryan Reynolds movie 6 Underground each person is called by a no. 1, 2, 3, 4, 5, and 7. There is no 6.
Ryan Reynolds's character put the team together and he gave others the corresponding numbers.
Even in the movie, someone at one point asks, One aka Ryan Reynolds, why there is no Six. But he didn't answer it.
So why is there no six? Is it mentioned in the movie?