mongoose value number to string format of digit 15 change to character e+15

i have a problem, when trying to create a new field in mongoose aggregate.
when I try to convert a number to a string. where the number has digits 15 and above.

but the result of adding the string e+15

        $addFields: {
          stringCode: {$toString : "$number_code"}
        $lookup: {
          from: "member",
          localField: "number_code", //string
          foreignField: "stringCode", // intiger to string
          as: "member",

the example number I’m trying to change is 123456789123456

and the result is “stringCode”: “1.2345e+15”

I hope the result is “123456789123456”