For a six-digit number, the sum of the numbers in every adjacent three digits is 15, and the numbers in the thousand and tens digits are 7 and 3 respectively. What is the six-digit number?
一个六位数，每相邻三位上的数之和是15，其中千位和十位上的数分别是7和3，这个六位数是多少．
<result>537_537</result>