One possible solution:
plot(rand(100,1).*1e6)
set(gca, 'YTickLabel', num2str(get(gca,'YTick')','%d'))
Obviously you can customize the formatting to your liking
Another example for the x-axis ticks. In this case, the labels would overlap each other. One possible solution is to use the XTICKLABEL_ROTATE function from the File Exchange.
plot(5.77*1e6:5.77*1e6+9, rand(1,10))
set(gca, 'XTickLabel', num2str(get(gca,'XTick')','%d')) %#'
xticklabel_rotate([],45) %# rotate the xtick-labels 45 degrees