How to convert NumberLong to Date in MongoDB's shell?

Question

I am storing unix timestamp as MongoDB's NumberLong type (millisecond) , how to convert to human readable date string in the Mongo shell?

Answer 1

NumberLong(123123123123131).toNumber().toString()

Answer 2

For my own future reference (and incorporating the other answers):

db.mycollection.aggregate([
  {$match:{"userId":"d1792d83-d854-44d5-9jc5-e3e20435958b"}},
  {$project:{newDate:Date("$numberLongDate")}}
])