In an eight-digit number, the number in the thousands place is 6, the number in the tens of thousands place is 5, and the sum of any adjacent three numbers is 18. What is this number?
一个八位数，千位上的数字是6，万位上的数字是5，任意相邻的三个数位上的数字之和都是18，这个数是多少．
<result>56_756</result>