The sum of the four digits of a four-digit number whose thousands digit is 1 is 21. The tens digit of this four-digit number is the same as the hundreds digit, and the thousands digit and the ones digit of this four-digit digit are reversed to obtain The new four-digit number is greater than the original four-digit number by 4995. What is the original four-digit number?
一个千位数字是1的四位数的四个数字之和是21，这个四位数的十位数字与百位数字相同，把这个四位数的千位数字与个位数字对换，得到的新四位数比原四位数大4995原四位数是多少．
<result>1_776</result>