Question

Missing number in following sequence is
4,9,25,?,121,169

Answer 1

$4=2^2\\9=3^2\\25=5^2\\?=?\\121=11^2\\169=13^2$

Observe that $2,3,5,\_,11,13$ are all prime and if you plug $7$ in that blank, you get the first $6$ primes. A possible value for the missing number is $7^2=\boxed{49}$

Answer 2

Square of 7 49 as prime number series