Every subgroup is a direct factor iff direct product of elementary Abelian groups

From Groupprops

Statement

The following are equivalent for a group:

  1. Every subgroup of the group is a direct factor.
  2. The group is either trivial or a direct product of elementary Abelian groups. In other words, it is a direct product of Abelian p-groups for possibly different primes p where each p-group is an elementary Abelian group.

The implication (2) implies (1) requires the use of the axiom of choice.