The supergroup’s comeback album Arirang , their first full-length LP in six years, moved 641,000 total copies, including 532,000 in pure album sales BTS are back in a big way. The supergroup’s comeback album Arirang , their first full-length LP in six years, brought in record-breaking first week sales. Arirang sold 641,000 total copies in its first week of release — the most by a group since Billboard started tracking streaming numbers in 2014 — including 532,000 in pure album sales. That latter figure is the biggest by a group in over a decade, Billboard reports ; it’s the most pure album sales by a group since One Direction’s Midnight Memories in 2013. Within 24 hours of arrival, Arirang racked up the most single-day streams for an album released this year on Spotify . BTS also brought in their all-time biggest streaming day on Apple Music. The numbers show that the record was worth the wait.…