The next number in the sequence is:
I got it by creating an algorithm that tested positive integers until a result was generated indicating that the question was answered correctly. The algorithm submitted an answer one at a time and waited for a response before submitting the next answer to make sure that the website wasn't overwhelmed.
For the curious - it took about 5 hours.
Hey, @Mr Pie's strange observation is correct!
An attempt to find a correlation between the numbers
$452801 \Rightarrow 773924 $, $[4+3,5+2,2+1,8+1,0+2,1+3]=[7,7,3,9,2,4]$
$773924 \Rightarrow 102410 $, $[7+3,7+2,3+1,9+1,2+2,4+3]=[10,9,4,10,4,7]$
$102410 \Rightarrow 471056 $,$[1+3,0+2,2+1,4+1,1+2,0+3]=[4,2,3,5,3,3]$
$471056 \Rightarrow 216101 $,$[4+3,7+2,1+1,0+1,5+2,6+3]=[7,9,2,1,7,9]$
Just wanted to get this out there because I feel very confident about the first two correlations although the next two are very flimsy. Maybe this edit will generate more interest in this question and someone will finally find the answer