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);