Please enter a number between 2 and 239 [inclusive].
The isomorphism classes of your number will then be listed.
(You can also simply hit "Find Groups" to have a number chosen at random.)

20 = 2² * 5
Thus there are two nonisomorphic abelian groups of order 20,
(1) Z₂ ⊕ Z₁₀
(2) Z₂₀