I'm interested as to where you found that number as all the sources I found indicated 91 billion years.

Yes. As far as we know according to the laws of physics as we understand them, rocky bodies like the Earth do not have a lifespan like stars do, and unless they are consumed by something else, they are likely to drift around forever.

If the earth manages to avoid being consumed by the Sun dying, it will probably stick around basically forever.

However, eventually (in tens of billions of years) the liquid layers of the Earth's core and mantle will cool and solidify, which will have significant effects on the surface. The Earth's magnetic field will disappear, leaving it unprotected from ionizing radiation and cosmic rays. That will eventually lead to the atmosphere being lost along with all liquid water and Earth will end up looking more like Mars (which we think also once had oceans and an atmosphere). Luckily, we shouldn't have to worry about that for at least 90 billion years.