Wow ! I understand your shock. I shook and vibrated a little when I looked at this one too.
The reason for our shock is all the extra junk in the question, put there just to shock and distract us.
"Neutron star", "5.5 solar masses", "condensed burned-out star". That's all very picturesque, and it excites cosmic fantasies in out brains when we read it, but it's just malicious decoration. It only gets in the way, and doesn't help a bit.
The real question is:
What is the acceleration of gravity 2000 m from the center of a mass of 1.1 x 10³¹ kg ?
Acceleration of gravity is
G · M / R²
= (6.67 x 10⁻¹¹ N·m²/kg²) · (1.1 x 10³¹ kg) / (2000 m)²
= (6.67 x 10⁻¹¹ · 1.1 x 10³¹ / 4 x 10⁶) (N) · m² · kg / kg² · m²
= 1.83 x 10¹⁴ (kg · m / s²) · m² · kg / kg² · m²
= 1.83 x 10¹⁴ m / s²
That's about 1.87 x 10¹³ times the acceleration of gravity on Earth's surface.
In other words, if I were standing on the surface of that neutron star, I would weigh 1.82 x 10¹² tons, give or take.
