The island of Batam, which lies within the central core group of islands (the Riau Archipelago), contains a majority of the province's population. Since becoming part of an economic zone with Singapore in 2006, it has experienced high population growth rates. Other highly populated islands in the Riau Archipelago include Bintan and Karimun, while the archipelago also includes islands such as Bulan and Kundur. There are around 3,200 islands in the province, which has its capital at Tanjung Pinang in the south of Bintan Island. The Riau Islands province includes the Lingga Islands to the south of the main Riau Archipelago, while to the northeast lies the Tudjuh Archipelago, between Borneo and mainland Malaysia; the Tudjuh Archipelago consists of four distinct groups – the Anambas Islands, Natuna Islands, Tambelan islands and Badas Islands — which were attached to the new province, though not geographically part of the Riau Archipelago. The 2015 census count was 1,968,313, less than estimated but it was still the second fastest growing province in Indonesia.