what's the mass of the Sun?

The Sun is losing mass at the rate of about 10 million tonnes per second because it is using its hydrogen fuel in the core and at the same time is continuously blowing off some of its atmosphere. However, even at this rate it would be a very long time before the Sun ran out of mass.

How long will it be then before all the Sun's mass is gone?
Divide the total mass by the how much it loses each second.
Mass/loss-rate = 2 x 10³⁰ / 10¹⁰ = 2 x 10²⁰ seconds, or about 6 thousand billion years.

Don’t worry though, a lot of other things will happen to the Sun long before this loss of mass becomes a problem.

The Sun is very greedy. It has 99.85% of all the mass in our solar system.