PHP has the rand() function:
$int= rand(1262055681,1262055681);
It also has mt_rand(), which is generally purported to have better randomness in the results:
$int= mt_rand(1262055681,1262055681);
To turn a timestamp into a string, you can use date(), ie:
$string = date("Y-m-d H:i:s",$int);
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…