Solving from the original equation, we get
x2=211(−117x1+38)=−6x1+2+211(9x1−4)x3=211(9x1−4)∈Zx1=91(21x3+4)=2x3+91(3x3+4)x4=91(3x3+4)∈Zx3=31(9x4−4)=3x4−1−31
The last equation indicates: x3,x4 cannot both be integers, so the indeterminate equation has no solution.