Answer
$1.2926\times 10^{13}y$
Work Step by Step
We find the half life and we convert the units
$t_{\frac{1}{2}}=\frac{0.693}{1.7\times 10^{21}}\times \frac{1h}{3600s}\times \frac{1d}{24h}\times \frac{1y}{365d}=1.2926\times 10^{13}y$
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