Jim Miller provides an overview of longevity insurance.  It is basically an immediate annuity that doesn’t start paying until around age 85.

These products are still new so I’m not confident that pricing has stabilized yet (i.e., enough competition to ensure you are getting your money’s worth).  The other issue is that they are not inflation indexed so you need to take that into account.  Otherwise, I think these products are a great addition to the array of immediate annuities that already exist.