AngularJS: input[number] with placeholder & ng-model

I have the following input field in my view

<input type="number" min="0" placeholder="7500" ng-model="totalClicks" required>

What I want now is to set the model variable total totalClicks to an initial value that is not reflected to the UI unless the user makes an input.

If I initialize with

$scope.totalClicks = {};

or

$scope.totalClicks = '';

then the placeholder is shown correctly until the user makes an input. However, the model variable totalClicks is not updated and remains as initialized.

If I set it to 

$scope.totalClicks = 0;

then 0 is shown in the input and the placeholder isn't but the model is updated.

Any advices?

UPDATE:

Added

$scope.funnel = {};
$scope.funnel.totalClicks = 9;
<input type="number" min="0" placeholder="7500" ng-model="funnel.totalClicks" required>

Now the placeholder is shown on page load but $scope.funnel.totalClicks remains 9 when I change the input

UPDATE #2: Here's an example on plunker. There're 2 text boxes bound to the same model therefore when I change the model in one input box the other one should change as well. (Example includes ionic framework) http://plnkr.co/edit/F4fOGMBA8eFJ9vdyuDvm

Following is the working example for updating the totalClicks ngModel.

<html ng-app="ExamplesApp">  
  <head> 
    <script src="angular.js"></script>   
  </head>  
 <body ng-controller="ExCtrl">
   <input type="number" min="0" placeholder="7500" ng-model="totalClicks" required>
   <button ng-click="clicks()">Click</button>   
   <script type="text/javascript">
     angular.module('ExamplesApp',[]);
     angular.module('ExamplesApp')
      .controller('ExCtrl',function($scope){
        $scope.totalClicks = '';         
        $scope.clicks= function(){
          alert($scope.totalClicks);
        };
      });
   </script>
 </body>
</html>

JSFiddle : http://jsfiddle.net/StT2y/2/

define the value and model as a property on the totalClicks object.

$scope.totalClicks = {}
$scope.totalClicks.amount = 0;

<input type="number" min="0" placeholder="7500" ng-model="totalClicks.amount" required>