दिए गए विकल्पों में से संबंधित संख्या का चयन कीजिए। 21 : 3 :: 574 : ?

Select the related number from the given alternatives. 432 : 9 :: 512 : ?

Choose the option that is related to the first number in the same way that the fourth number is related to the third number and the sixth number is related to the fifth number. 529 : ? :: 729 : 900 :: 441 : 576