Russian billionaire Mikhail Prokhorov, looking to protect a $165 million investment in the Nassau Coliseum, is pressuring the New York Islanders to play a significant number of games at the Long Island arena in the 2018-2019 season, The Post has learned. Prokhorov, who owns Brooklyn’s Barclays Center, also bought the company that under Bruce Ratner promised Nassau County that a professional hockey team would play at the recently renovated suburban arena — a promise that helped the Nassau Events Center in 2013 win a contract to manage the facility. But no professional hockey team now plays at the 13,900-seat Uniondale, NY, arena and local officials might move soon to hold Prokhorov’s NEC in default, sources tell The Post. Charles Wang, who owned the Islanders in 2013, had agreed to play some games at the Nassau Coliseum, but sold the team in 2014.