VF Remoting - Curious Behavior of NumberOfEmployees field in Account

Apex Controller with Remoting Method

public class RemoteApexTestNumOfEmployees {
    @RemoteAction
    public static void putAccount(Account a){
		
        update a;
        
    } 
}

VF Page to test NumberOfEmployees

<apex:page docType="html-5.0" controller="RemoteApexTestNumOfEmployees" >
    <script>
    
    function putAccount(){
        var account = {
            Id : document.getElementById("accountPutId").value,
            NumberOfEmployees : document.getElementById("accountPutNumEmp").value,
            AnnualRevenue : document.getElementById("annRev").value
        };
        console.log(account);
        RemoteApexTestNumOfEmployees.putAccount(account, function(result, event){
            console.log(event);
        });        
    }
    </script>
    <div>
        <input id="accountPutId" type="text" placeholder="Id"/>
        <input id="accountPutNumEmp" type="number" placeholder="Num Of Employees"/>
        <input id="annRev" type="number" placeholder="Revenue"/>
		<button onClick="putAccount()">
            Go
    </button>
    </div>
</apex:page>