The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  2  1  1  1  1
 0  2  0  0  0  2  2  2 2a  0  2 2a 2a 2a 2a  0  2 2a^2+2 2a^2+2a 2a^2  0
 0  0  2  0  0 2a^2+2 2a^2+2a+2 2a^2+2a 2a^2+2a  2 2a+2 2a^2+2  0  2 2a^2+2a+2 2a 2a+2  0 2a^2+2a 2a^2  0
 0  0  0  2  0  2 2a^2+2a+2 2a 2a+2 2a^2 2a^2+2  0 2a^2+2a+2  2 2a 2a^2+2a 2a+2 2a^2 2a+2 2a^2  2
 0  0  0  0  2 2a^2+2 2a+2 2a 2a^2+2a+2 2a 2a^2 2a^2 2a+2  0 2a  2 2a^2 2a^2+2a  0 2a^2+2a+2 2a^2+2

generates a code of length 21 over GR(64,4) who´s minimum homogenous weight is 112.

Homogenous weight enumerator: w(x)=1x^0+175x^112+1379x^120+2548x^128+4249x^136+28672x^140+7609x^144+200704x^148+9149x^152+5635x^160+2023x^168

The gray image is a code over GF(8) with n=168, k=6 and d=112.
This code was found by Heurico 1.16 in 9.27 seconds.