For a four-digit number, the number in the ones place is 1 less than the number in the hundreds place, the number in the hundreds place is three times the number in the tens place, and the number in the thousands place is half of the number in the hundreds place. This number is greater than 3000 and less than 4000. What is this number?
一个四位数，个位上的数字比百位上的数字少1，百位上的数字是十位上的数字的3倍，千位上的数字是百位上的一半．这个数比3000大，比4000小，这个数是多少？
<result>3_625</result>