Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the lowest 2013 population estimate of south africa, which has a percentage greater than 19.8 and a 2011 population greater than 51,770,561?

### Inputs:
table_name: table, columns: ['Rank', 'Province', 'Population (2011)', 'Percentage', 'Population Estimate (2013)']

### Response:
SELECT MIN Population Estimate (2013) FROM table WHERE Percentage > 19.8 AND Province = south africa AND Population (2011) > 51,770,561