The sum of the digits of the four-digit number 2013 is 6, and each digit is different. Among the four-digit numbers with these properties, in ascending order, what number is 2013?
四位数2013的各位数字和为6，且各位数字均不相同．在具有这些性质的四位数中，按由小到大顺序排列，2013是第多少个．
<result>7</result>