Rounding Digits in a new Way

Find a 9-digit number, which you will gradually round off starting with number placed at units, then tens,hundreds, etc.,until you get the last numeral, which you do not round off. The rounding alternates (down,up,down $\ldots$ ) which means that the first number from right is rounded down while the second number from the right is rounded up and so on.

After rounding off 8 times, the final number is 500,000,000 . The original number is divisible by 6 and 7, all the numbers from 1 to 9 are used, and after rounding, four times the sum of the not rounded numerals equals 24.

What is the number?