Question about 6 unit deal in Iowa

[Joe T.]

I wanted to get thoughts on this deal in Iowa:

6 unit side-by-side townhouses. Each 2br/1ba. In C neighborhood with minimal opportunity for appreciation. 

Price: 170k
Rent: $500/unit for $3000 a month = $36,000/yr.
2018 expenses: $12000, plus property management of $3600 = $15,600/yr

Net Operating Income comes out to $20,400/yr. 
Financing is on a 5 yr ballon, on 25 yr amortization, with 20% down.

I'm looking for cash flow which this seems to have. However, I'm not sure whether there is risk in taking the loan with such a short 5 yr term. 
Looking for thoughts and feedback on how this should be approached.
Thanks!