Database: world_development_indicators
Question: What is the minimum of International migrant stock, total of heavily indebted poor countries?
SQL: SELECT MIN(T2.Value) FROM Country AS T1 INNER JOIN Indicators AS T2 ON T1.CountryCode = T2.CountryCode WHERE T1.OtherGroups = 'HIPC' AND T2.IndicatorName = 'International migrant stock, total'