It's about 150,000 times as heavy as a Penny
In other words, the weight of a Penny is 0.00000590 times 0.000000420 megatonnes.(United States) (formally one-cent coin) (Union shield design, 2010-present)
The weight of a United States penny is 0.00000000000250 megatonnes. According to a 2010 report by the United States Mint, the cost of manufacturing and distributing a penny is $0.0179 — more than its face-value.
It's about 250,000 times as heavy as a Playing Card
In other words, the weight of a Playing Card is 0.00000430 times 0.000000420 megatonnes.(ISO 216 B8 size, 2.5" x 3.5")
A single ISO 216 B8-size playing card weighs 0.00000000000180 megatonnes. 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 one-three-hundred-thousandth as heavy as The CN Tower
In other words, 0.000000420 megatonnes is 0.0000035620 times the weight of The CN Tower, and the weight of The CN Tower is 280,740 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 0.117910 megatonnes. 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.
It's about 300,000 times as heavy as a Paper Clip
In other words, the weight of a Paper Clip is 0.00000330 times 0.000000420 megatonnes.(average)
Notwithstanding the tremendous variation in sizes and materials, a typical paperclip weighs about 0.00000000000140 megatonnes. 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 400,000 times as heavy as a Jelly Bean
In other words, 0.000000420 megatonnes is 380,000 times the weight of a Jelly Bean, and the weight of a Jelly Bean is 0.00000260 times that amount.(for Jelly Belly beans; approximate)
Made of sugar, corn syrup, and pectin, a single jelly bean weighs about 0.00000000000110 megatonnes. President Ronald Reagan cited jelly beans as his favorite candy and 0.00000320 megatonnes of the candies were served at his first inauguration in 1981.
It's about one-five-hundred-thousandth as heavy as The Sears Tower
In other words, 0.000000420 megatonnes is 0.0000020810 times the weight of The Sears Tower, and the weight of The Sears Tower is 480,500 times that amount.(officially "Willis Tower" as of 2009) (Chicago, Illinois)
The Willis Tower weighs approximately 0.20180 megatonnes. 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 550,000 times as heavy as a Nail