Sort Products by SKU Number

Yes you sure can. Open up your functions.php file in your child theme. If you are in your dashboard go to APPEARANCE > EDITOR > from the list of files on the far right look for functions.php
Add this line of code at the end of the file. 

add_filter('woocommerce_get_catalog_ordering_args', 'wcs_woocommerce_catalog_orderby_sku');
function wcs_woocommerce_catalog_orderby_sku( $args ) {
        $args['orderby'] = 'meta_value';
        $args['meta_key'] = '_sku';
}