Error Converting Data Type Nvarchar To Bigint

I getting the above error can someone please help me solve it, here is the code:

public void InsertHost()
    {
        // TODO
        // - Call stored procedure to write to a log file writeToLog
        using (SqlConnection cn = new SqlConnection(ConfigurationManager.AppSettings["ConnectionString"]))
        {
            SqlCommand cmd = new SqlCommand("writeToLog", cn);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@pAction", "action");
            cmd.Parameters.AddWithValue("@pHostName", "Hostname");
            cmd.Parameters.AddWithValue("@pUserNUm", "requestorID");
            cn.Open();
            cmd.ExecuteNonQuery();
        }
    }

Here is the storedprocedure:

ALTER PROCEDURE dbo.writeToLog
(@pAction varchar(10), @pUserNUm bigint, @pHostName varchar(25))
AS INSERT INTO dbo.hostNameLog
                      (action, requestorID, HostName)
VALUES     (@pAction, @pUserNUm, @pHostName)

Here is the table:

HostName - varchar, action - varchar, requestorID - bigint

I can't seem to find the error.