It may be not enoough for a 52 years old man. 62 years old may be OK. The following uncertainty will affect you.
1. Do not know what will be the cost for health insurance in the future. Obamacare will take money from rich to help poor. You are not qualified for medicare until 65.
2. Paper Money devalue can be very fast. The buying power can be cut to half in 10 -20 years.
3. You could live longer than planneed such as 90 YO is very common. End up you run out money before you die.