Mysql: which datatype must be used to store mongo db document's object id

Question

The use case is, I have some of our product data present in Mongodb, while some data is present in MySQL.

So, the data that will reside in MySQL is:

product_skus (MySQL table) having columns - 
product_sku_id,
product_id (this will be the ObjectId of the product document stored in Mongodb)

product (Mongo Collection)
_id (ObjectId - referenced in product_skus table as product_id)
and some other product attributes...

To create a connection between the two, I need to store document's object id in MYSQL. Which datatype should I use for storing objectId in MYSQL?