One gets the impression that there are "millions" of them !! But, in fact there are ONLY 55 as follows:
1000000002 , 1000000011 , 1000000020 , 1000000101 , 1000000110 , 1000000200 , 1000001001 , 1000001010 , 1000001100 , 1000002000 , 1000010001 , 1000010010 , 1000010100 , 1000011000 , 1000020000 , 1000100001 , 1000100010 , 1000100100 , 1000101000 , 1000110000 , 1000200000 , 1001000001 , 1001000010 , 1001000100 , 1001001000 , 1001010000 , 1001100000 , 1002000000 , 1010000001 , 1010000010 , 1010000100 , 1010001000 , 1010010000 , 1010100000 , 1011000000 , 1020000000 , 1100000001 , 1100000010 , 1100000100 , 1100001000 , 1100010000 , 1100100000 , 1101000000 , 1110000000 , 1200000000 , 2000000001 , 2000000010 , 2000000100 , 2000001000 , 2000010000 , 2000100000 , 2001000000 , 2010000000 , 2100000000 , 3000000000 , Total = 55