From wikipedia:
His length is 15 meters for the male and around 17 meters for the female. They are born measuring 3 to 5 meters from snout to tail. Its weight ranges from 40 tons (adult weight).
Calluses can be observed, which are raised areas of skin more than approximately 18 cm thick, of a horny consistency, located in different parts of the head. The distribution, dimension and shape of the calluses vary from one whale to another but do not change with growth. Functioning like fingerprints, they identify each animal throughout its life. These calluses, developed in the fetal stage and dark gray in color, have dense populations of small amphipod crustaceans called cyamids (Cyamidae, whale lice) and are sometimes interspersed with cirripeds that make the calluses look white, yellow, orange or light pink. Normally, they are distributed along the upper margin of the lower lip, jaw, dorsal surface of the face and over the eyes. The most important callus due to its size is the "bonnet", located at the tip of the snout.
Inside its curved mouth, the upper jaw holds about 260 horny plates or baleen originally called "baleen", from which the Spanish name whale is derived. These beards measure about 2.50 m long. When whales feed, they serve as filters or strainers to retain their main food, krill and copepods.
Males have the largest sexual organs in the entire animal kingdom. Its testicles can weigh up to 525 kg each, with dimensions of 2 m x 78 cm (almost 1% of its body weight, 10 times larger than those of the blue whale), and its penis can reach a length of 2.7 m.2​
Scientists have related these proportions to the so-called sperm competition, present in this and other species.3