64s6+t6

That's the sum of two cubes:

64s6 is equal to (4s2)3

t6 is equal to (t2)3

The sum of two cubes A3+B3 factors as (A+B)(A2-AB+B2)

(A+B)(A2-AB+B2)

let A = 4s2, B = t2

(A+B)(A2-AB+B2) = (4s2+t2)[(4s2)2-(4s2)(t2)+(t2)2] = 

(4s2+t2)[16s4-4s2t2+t4]  

(4s2+t2)(16s4-4s2t2+t4)

Edwin