In 'Anthem' by Ayn Rand, what is the protagonist's assigned name?

In Ayn Rand’s Anthem, the protagonist’s assigned name is Equality 7-2521.

The name reflects the society’s attempt to erase individuality. Children are raised collectively, separated from their parents, and assigned numbered names rather than personal identities. Equality 7-2521 is designated a Street Sweeper, even though he is unusually intelligent and dreams of becoming a Scholar.

His assigned name is easy to confuse with the names of other characters. International 4-8818 is his fellow Street Sweeper and only friend, while Liberty 5-3000 is the young woman he loves. Later, after escaping into the forest, Equality 7-2521 discovers the word “I” and chooses the new name Prometheus. Liberty 5-3000 likewise adopts the name Gaea.

Thus, Prometheus is his chosen identity later in the novella, not the name assigned to him by the collectivist state. The original name, Equality 7-2521, is the canonical answer for this question.