Check the number assignment is External or Internal based on Account group?

I want to validate in my program whether the given account group in vendor creation XK01 will accept External number or internal number range.

Scenario:

I want to create some vendor's with SAP internal number range and some vendor's with external number which is given in the excel sheet.

Functional:

External number range allowing is configured in SPRO to Account group.

Technical:

The flag for external number range is saved in NRIV table.

Question;

Is there any FM to find the given account group allows external number

or which all are the related tables which i can join to get the number range flag by passing Account group as the condition.

Thank you