find common ratio in geometric sequence Please Help Me to answer this question

now im using this formula $$a_n = a_1r^{n-1}$$

now i got a question if the given term is only

$$a_n = 3,960,298,332$$
$$a_1 = 92$$
$$ratio = ??$$
$$n = 16 $$

but i tried $${3960298332 \over 92}$$ $$=43046721$$ 
$$\sqrt[15]{43046721}$$

and the result is $$3.227968874176$$

now is possible to get double in common ratio or its wrong?

. any answer is highly appreciated thank you
$a_n = a_1r^{n-1}$

$3960298332 = 92 \cdot r ^{n-1}$

$43046721=r^{16-1} \Rightarrow = 43046721=r^{15} $

Take log (base 10) both side,
$7.6339 = 15 \log r \Rightarrow \frac{7.6339}{15}=\log r$

$\log r = 0.5089$

$r = 10^{0.5089} = 3.2277$.(truncated).
$a_n = a_1r^{n-1}$

$3960298332 = 92 \cdot r ^{n-1}$

$43046721=r^{16-1} \Rightarrow = 43046721=r^{15} $

Take log (base 10) both side,
$7.6339 = 15 \log r \Rightarrow \frac{7.6339}{15}=\log r$

$\log r = 0.5089$

$r = 10^{0.5089} = 3.2277$.(truncated).