python整数转字符串

num = int(input('请输入一个整数：'))
s = ''
def int_to_str(val):
    li = []
    while val > 0:
        digit = val % 10
        li.append(digit)
        val //= 10
    return li
lst = int_to_str(num)
for i in lst[::-1]:
    s+=str(i)
print(s, type(s))