For a four-digit number, the sum of the digits in each digit is 16. It is known that the number in the tens place is three times that of the ones place, the number in the hundreds place is 3 times more than the ones place, and the number in the thousands place is twice that of the hundreds place. How much is this four-digit number?
一个四位数，各个位数上的数字之和是16．已知十位上的数字是个位的3倍，百位的数字比个位多3，千位的数字是百位的2倍．求这个四位数是多少？
<result>8_431</result>