Given edge of wooden block (a) = 21cm

Given diameter of hemisphere = edge of cube

Radius = 21/2 = 10.5cm

Volume of remaining block = volume of box – volume of hemisphere

Surface area of box = 6a^{2} ........(1)

Curved surface area of hemisphere = 2πr^{2} ..........(2)

Area of base of hemisphere = πr^{2}

So remaining surface area of box = (1) – (2) + (3)

Remaining surface area of box = 2992.5cm^{2}

Volume of remaining block = 6835.5cm^{3}