A vampire number is a non-negative number that can be factored into two numbers (fangs) each with half as many digits as the original where the - two factors contain all the digits of the original, in any order. Both - fangs may not have trailing zeros. + two factors contain all the digits of the original, in any order. One but + not both fangs may have trailing zeros.
For example 1260 = 21*60, 1395 = 15*93, 1435 = 35*41,