Short answers, pulled from the story.
Russia's internationally recognized land border runs 22,407 kilometers in total. This makes Russia the country with the second-longest land border in the world, behind China, which has a land border of 22,457 kilometers.
Russia shares land borders with fourteen sovereign states. It also has narrow maritime boundaries with the United States and Japan, and borders two internationally unrecognized breakaway territories, Abkhazia and South Ossetia.
The longest land border Russia shares with any single country is the Kazakhstan-Russia border, which runs 7,512.8 kilometers. This makes it one of the longest bilateral land borders on Earth.
The borders of the Russian Federation were mostly drawn since 1956, with only minor changes such as adjustments with China. They remained the same following the dissolution of the Soviet Union.
In 2014, Russia annexed Ukraine's Crimean peninsula, altering de facto borders with Ukraine in a move that remains internationally unrecognized. In 2022, Russia further annexed Donetsk, Kherson, Luhansk, and Zaporizhzhia oblasts, again changing de facto borders with Ukraine.
The formal USSR-USA Maritime Boundary Agreement defines a maritime boundary of 49 kilometers between Russia and the United States. Russia also has a maritime boundary of 194.3 kilometers with Japan.