igraph_empty(&g,0,true);
igraph_add_vertices(&g,131071,0);//17
igraph_add_vertices(&g,262143,0);//18
igraph_add_vertices(&g,524287,0);//19
igraph_add_vertices(&g,1048575,0);//20
igraph_add_vertices(&g,2097151,0);//21
igraph_add_vertices(&g,4194303,0);//22
igraph_add_vertices(&g,8388607,0);//23
igraph_add_vertices(&g,16777215,0);//24
igraph_add_vertices(&g,16777216,0);//24+1 does not work
as you can see, I'm testing the max value available of node id.