Permütasyon neden hatalı?

import itertools

def next_smaller(n):
 digits_list = []

 for char in str(n):
 digits_list.append((int(char)))

 digits_list.sort()

 possible_numbers_list = list(itertools.permutations(digits_list))

 for item in possible_numbers_list:
 repetition = possible_numbers_list.count(item)
 if repetition > 1:
 for rep in range(repetition - 1):
 possible_numbers_list.remove(item)

 print(len(possible_numbers_list))

next_smaller(111456)

import itertools

def next_smaller(n):
    n = str(n)
    possible_numbers_list = set(itertools.permutations(n))
    print(len(possible_numbers_list))

next_smaller(111456)