
It's about 650,000 times as heavy as a Nail.
In other words, the weight of a Nail is 0.00000150 times 521 kilograms.
(for 15gauge, 2inch, finishing nails)A twoinch finishing nail weighs 0.00079 kilograms. Nails have been in use for more than 5,400 years and were ven used as a medium of exchange in ancient times.
It's about 450,000 times as heavy as a Jelly Bean.
In other words, the weight of a Jelly Bean is 0.00000210 times 521 kilograms.
(for Jelly Belly beans; approximate)Made of sugar, corn syrup, and pectin, a single jelly bean weighs about 0.0011 kilograms. President Ronald Reagan cited jelly beans as his favorite candy and 3,200 kilograms of the candies were served at his first inauguration in 1981.
It's about 350,000 times as heavy as a Paper Clip.
In other words, the weight of a Paper Clip is 0.00000270 times 521 kilograms.
(average)Notwithstanding the tremendous variation in sizes and materials, a typical paperclip weighs about 0.0014 kilograms. The country of Norway has used the paper clip as something of a national symbol since the end of World War II based on the erroneous notion that the paperclip was invented by a Norwegian, Johan Vaaler. However, the paperclip had already been in existence for at least 30 years by the time of Vaaler patented his paperclip design.
It's about 300,000 times as heavy as a Playing Card.
In other words, 521 kilograms is 290,000 times the weight of a Playing Card, and the weight of a Playing Card is 0.00000340 times that amount.
(ISO 216 B8 size, 2.5" x 3.5")A single ISO 216 B8size playing card weighs 0.0018 kilograms. Although this size is the most common home playing card, many casinos use "bridge size" cards — 2,640 sq. mm (4.036 sq. in) smaller in area.
It's about 200,000 times as heavy as a Penny.
In other words, 521 kilograms is 210,000 times the weight of a Penny, and the weight of a Penny is 0.00000480 times that amount.
(United States) (formally onecent coin) (Union shield design, 2010present)The weight of a United States penny is 0.0025 kilograms. According to a 2010 report by the United States Mint, the cost of manufacturing and distributing a penny is $0.0179 — more than its facevalue.
It's about 150,000 times as heavy as a Die (Dice).
In other words, the weight of a Die (Dice) is 0.00000770 times 521 kilograms.
(for sixsided, 16 mm, rounded cube)A die, of the size most commonly used in board games and casinos, typically weight 0.0041 kilograms. The use of dice and dicelike tools predates written history, with the oldest known examples belonging to a 5,000year old backgammon set uncovered during an archaeological dig in modernday Iran.
It's about 100,000 times as heavy as a sheet of Paper.
In other words, the weight of a sheet of Paper is 0.00001000 times 521 kilograms.
(for US Letter, a.k.a. ANSI A; 215.9mm by 279.4mm (8.5 in x 11 in); 20lb)The weight of a ream (500 sheets) of 9 kilograms, 8.5 inch x 11 inch paper is 2 kg, each sheet weighing 0.005 kilograms. Paper of this size has a thickness of 0.004 caliper (0.1 mm). 
