Complete the series - 21, 25, 33, 49, 81,?

Question

A number series is given with one term missing, find it.
21, 25, 33, 49, 81,?

Comments

Too simple puzzle, please avoid trivial puzzle...

Answer 1

The pattern is 21+ 4, 25+ 8, 33+ 16, 49+ 32,.... i.e. + 2*2, + 2*2*2, + 2*2*2*2, + 2*2*2*2*2,...
.'. Missing number = 81 + 2*2*2*2*2*2 = 81 + 64 = 145.

Answer 2

145

The difference between consecutive numbers in the sequence is an increasing power of 2 , i.e., 2^2, 2^3, 2^4, 2^5, 2^6, etc.