Sun gear for a mechanical reduction gear of an aircraft turbomachine

A sun gear for a mechanical reduction gear of an aircraft turbomachine, the sun gear having an annular shape about an axis, the sun gear comprising:

• an inner annular part including coupling splines at its inner periphery;
• an outer annular part having at its outer periphery at least one meshing toothing, the outer part extending around the inner part;
• and
• an annular web connecting the inner and outer parts, the annular web being located between the inner and outer parts and having a shape giving the sun gear a capacity for elastic deformation,
• wherein the inner part includes two independent rings each having splines, and/or the outer part includes two independent rings each having a toothing, and
• wherein the web has two annular legs connected respectively to the two rings.