It's about 0.0000000000000000000000000003 times as heavy as The Sun.
In other words, 521 kilograms is 0.000000000000000000000000000260 times the weight of The Sun, and the weight of The Sun is 3,800,000,000,000,000,215,419,453,440.000000000000000000000000000000 times that amount.The sun has a mass of 2,000,000,000,000,000,179,380,838,125,797,376.000000000000000000000000000000000000 kilograms which represents 99.9% of the solar system's total mass. 98.7% of the sun's mass consists of hydrogen and helium — respectively the lightest and second-lightest elements in the universe.
It's about 0.00000000000000000000009 times as heavy as The Earth.
In other words, 521 kilograms is 0.0000000000000000000000872170 times the weight of The Earth, and the weight of The Earth is 11,465,999,999,999,999,475,712.0000000000000000000000000000 times that amount.The mass of the planet Earth is 5,973,599,999,999,999,505,072,128.000000000000000000000000000000 kilograms. The element iron makes up about 32% of that mass, or 1,917,499,999,999,999,942,328,320.000000000000000000000000000000 kilograms.
It's about 0.00000009 times as heavy as The Great Pyramid of Giza.
In other words, 521 kilograms is 0.0000000880 times the weight of The Great Pyramid of Giza, and the weight of The Great Pyramid of Giza is 11,000,000 times that amount.(a.k.a. Pyramid of Khufu, a.k.a. Pyramid of Cheops) (Cairo, Egypt)
The Great Pyramid of Giza has an estimated mass of 5,900,000,000 kilograms. The 2,300,000 stones used in the construction of the pyramid weighed an average 2,300 kilograms and were quarried from distances of up to 805 km (500 mi) away.
It's about 0.0000007 times as heavy as The Golden Gate Bridge.
In other words, 521 kilograms is 0.0000006470 times the weight of The Golden Gate Bridge, and the weight of The Golden Gate Bridge is 1,550,000 times that amount.(San Francisco, California and Marin County, California) (Post 1986 weight reduction; total weight of bridge, anchorage, and approaches)
Following the completion of the 1986 project to eliminate excess material, the total weight of the Golden Gate Bridge — including its anchorages and approaches — is 805,000,000 kilograms. The two main cables in the spanning the bridge are spun out of a total of 129,000 km (80,200 mi) of wire.
It's about one-six-hundred-fifty-thousandth as heavy as The Empire State Building.
In other words, 521 kilograms is 0.000001570 times the weight of The Empire State Building, and the weight of The Empire State Building is 637,000 times that amount.(New York City, New York)
The Empire State Building weighs approximately 331,000,000 kilograms. About 4% of the building's weight is its 6,000 cu. m (200,000 cu. ft) of limestone façade.
It's about one-four-hundred-thousandth as heavy as The Sears Tower.
In other words, 521 kilograms is 0.0000025820 times the weight of The Sears Tower, and the weight of The Sears Tower is 387,300 times that amount.(officially "Willis Tower" as of 2009) (Chicago, Illinois)
The Willis Tower weighs approximately 201,800,000 kilograms. The outer wall surface of the Tower is covered with black anodized aluminum panels which would total 110,000 sq. m (28 acres) if laid out together.
It's about one-two-hundred-fifty-thousandth as heavy as The CN Tower.
In other words, 521 kilograms is 0.00000441860 times the weight of The CN Tower, and the weight of The CN Tower is 226,320 times that amount.(a.k.a. La Tour CN, a.k.a. Canadian National Tower, a.k.a. Canada's National Tower) (Toronto, Canada)
The CN Tower weighs approximately 117,910,000 kilograms. The Tower is home to the world's highest glass floor — a viewing area that allows visitors to look straight down 342 m (1,120 ft) to the ground below.