PHP random number storing in database issue

I am getting this weird kind of issue. The rand() function is generating random numbers correctly. But when it stores in the database the number is gone and only "8388607" number is stored in the MySQL database. I find this issue really strange.

$passcode=rand(); 
echo $passcode; //prints random number correctly

    $phone=$_GET['phone'];
    $email=$_GET['email'];
    $address=$_GET['address'];
    $documentid=$_GET['documentid'];

    $sql="insert into Transaction (date, amount, amountRs, passcode, isPaid, comment, clientid, receiverid) values ('$date','$amount','$amountRs','$passcode','no','$comment','$senderid[1]','$receiverid[1]')"; //stores "8388607" number in database