Setting ngTrueValue and ngFalseValue to numbers

You can use ngChecked, If the expression is truthy, then special attribute “checked” will be set on the element

<input type="checkbox" 
    ng-model="checkbox" 
    ng-true-value="1" 
    ng-false-value="0" 
    ng-checked="checkbox == 1" />

And you can use $scope.$watch to convert it to number

$scope.$watch(function(){
    return $scope.checkbox;
}, function(){
    $scope.checkbox = Number($scope.checkbox);
    console.log($scope.checkbox, typeof $scope.checkbox);
},true);

DEMO