Pass Integer attribute to lightning controller

I tried to pass integer attribute to controller but it didn't pass. Here is the code that i used.

Component

    <aura:component implements="force:appHostable,flexipage:availableForAllPageTypes" access="global" controller="BACSPaymentManagerController">
    <aura:attribute name="NextNDays" type="Integer" />
    <aura:attribute name="BACSConfirmation" type="Boolean" default="false"/>
    <aura:attribute name="paymentRecords" type="List" />
    <aura:attribute name="selectedRows" type="List" />
    <aura:attribute name="rowsSelected" type="List" />
    <aura:attribute name="columns" type="List" />   
    <lightning:card title="BACS" iconName="standard:file">
        <aura:set attribute="actions">
            <lightning:input type="Number" label="Next N days" value="{!v.NextNDays}" />
            <lightning:button class="slds-button_brand" label="Fetch Payments" onclick="{!c.fetchPayments}" />
        </aura:set>

            <div class="slds-col slds-size_12-of-12 slds-p-around_xx-small">

                <lightning:datatable data="{!v.paymentRecords}" columns="{!v.columns}" keyField="Id"
                                     selectedRows="{!v.selectedRows}" onrowselection="{!c.updateSelectedRows}"/>
        </div>
    </lightning:card>
</aura:component>

Controller

({
fetchPayments : function(component, event, helper) {
    helper.fetchPayments(component, event);
})

Helper

({
    fetchPayments : function(component, event) {
        var integerNextNDays = component.get("v.NextNDays");
        var action = component.get("c.getPayments");
        action.setParam({"nextNDays": integerNextNDays});
        action.setCallback(this, function(response){
            console.log(response.getState());
            if(response.getState() == 'SUCCESS'){
                if(response.getReturnValue() != undefined){
                    component.set("v.columns",[
                        {label:'Id', fieldName:'Id',type:'text'},
                        {label:'Name', fieldName:'Name',type:'text',sortable:'true'},
                        {label:'Amount', fieldName:'Amount_Paid__c', type:'currency',sortable:'true', typeAttribute:{currencyCode:'GBP'}},
                    ]);
                    component.set("v.paymentRecords", response.getReturnValue());
                }
            }
        });
        $A.enqueueAction(action);
    }
})

Apex Controller

public class BACSPaymentManagerController {
    @AuraEnabled
    public static List<Payment__c> getPayments(Integer nextNDays){
        if(nextNDays>0){
            try {
                Date dt = system.today() + nextNDays;
                List<Payment__c> allFilteredPayments = [SELECT Amount_Paid__c,Name,Name__c,Account_Number__c,Sort_Code__c,Contact__r.Client_Reference_BACS__c,Date_Due__c FROM Payment__c WHERE Payment_Type__c = 'BACS' AND Confirm_Payment__c = false AND Date_Due__c >= :system.today() AND Date_Due__c <=:dt];
                return allFilteredPayments;    
            }
            catch (Exception e) {
                // "Convert" the exception into an AuraHandledException
                throw new AuraHandledException('Darn it! Something went wrong: '
                                               + e.getMessage());    
            }    
        }
        else
            return [SELECT Amount_Paid__c,Name,Name__c,Account_Number__c,Sort_Code__c,Contact__r.Client_Reference_BACS__c,Date_Due__c FROM Payment__c WHERE Payment_Type__c = 'BACS' AND Confirm_Payment__c = false];

    }
}

Is there anything that i missed? Thanks