What is the maximum lifetime of superheavy elements consistent with observations?
Plutonium 244, half-life 82 million years, has been sought and claimed to have been found, but the experiments are said to have been flawed so plutonium actually has not been found. Samarium 146, half-life 103 million years, has not been reported found.
There are no known isotopes with half-life between 103 million years of Sm-146 and 704 million years of U-235.
So what is the maximum half-life of an unknown isotope, that it might not have been found on Earth?