ディレクティブの作成

controllers/directive/stringToNumber.js

/**
 *  controllers/directive/stringToNumber.js
 */

;(function() {
  'use strict';

angular.module('webApp')
  .directive('stringToNumber', function() {
    return {
      require: 'ngModel',
      link: function(scope, element, attrs, ngModel) {
        ngModel.$parsers.push(function(value) {
          return '' + value;
        });
        ngModel.$formatters.push(function(value) {
          return parseFloat(value, 10);
        });
      }
    };
  });

})();

使い方

index.html

<input type="number" string-to-number ng-model="account_number">