Use number validator to restrict the input to numbers with an optional range. (See integer for whole numbers validator).
<input type="text" ng:validate="number[:min][:max]"/>
angular.validator.number(value[, min][, max])
value – {string} –
value to validate
min(optional=MIN_INT) – {int} –
minimum value.
max(optional=MAX_INT) – {int} –
maximum value.