Relate Zoho Account id to AccountId in my web app DB

Relate Zoho Account id to AccountId in my web app DB

When using API and creating an Account (or any other record in any module), I know there is a way to get the newly created id and save it to my DB. But is there an opposite direction -- pass the account id (generated on my side) to the newly created Account? Is that what "Account Number" field is for? Or am I missing some other functionality that Zoho has?