There is a six-digit number, the number in the ones place is 8, and the number in the tens place is 6. The sum of any three adjacent numbers is 21. What is this six-digit number?
有一个六位数，个位上的数字是8，十位上的数字是6．任意相邻的三个数字之和都是21．这个六位数是多少？
<result>768_768</result>