A new number is a number that is not a permutation of any smaller number. 869 is not a new number because it is just a permutation of smaller numbers, 689 and 698. 509 is a new number because it can't be formed by a permutation of any smaller number (leading zeros not allowed).
Write a function that takes a non-negative integer and returns True if the integer is a new number and False if it is not.
is_new(3) ➞ True
is_new(30) ➞ True
is_new(321) ➞ False
is_new(123) ➞ True
A curious fact: out of the first one million integers, only 8002 are new.