Draft:Spy number

A spy number is a number whose digit sum is equal to its digit product, for example 1,124 is a spy number: 1+1+2+4 = 1*1*2*4. Consequently, changing the digit order of a spy number will always produce another spy number. For instance: 123, 132, 213, 231, 312 and 321 are all spy numbers.

The first spy numbers:0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 22, 123, 132...