Is Elros Elrond's brother?

Could you possibly clarify for me a detail from Tolkien's legendarium? I'm trying to understand the familial ties within the royal house of Númenor. Specifically, I'm wondering if Elros, the first King of Númenor, was indeed related to Elrond, the renowned elf-friend and advisor to many kings? More precisely, was Elros Elrond's brother, as some tales suggest, or was there a different relationship between them? I'm keen to get a clear picture of their lineage as it plays a crucial role in the larger narrative of Middle-earth. Thank you for your assistance in this matter.