Let's look at the difference between the consecutive numbers:
121 − 117 = 4
117 − 108 = 9
108 − 92 = 16
92 − 67 = 25
These differences form the sequence: $4, 9, 16, 25$ which are perfect squares:
\[
2^2, 3^2, 4^2, 5^2
\]
Continuing this pattern, the next difference should be:
\[
6^2 = 36
\]
Now subtract from the last term:
\[
67 - 36 = \boxed{29}
\]