It's about one-eight-hundred-thousandth as heavy as The Empire State Building
In other words, 0.000000420 megatonnes is 0.000001270 times the weight of The Empire State Building, and the weight of The Empire State Building is 787,000 times that amount.(New York City, New York)
The Empire State Building weighs approximately 0.3310 megatonnes. About 4% of the building's weight is its 6,000 cu. m (200,000 cu. ft) of limestone façade.
It's about 0.0000005 times as heavy as The Golden Gate Bridge
In other words, 0.000000420 megatonnes is 0.0000005220 times the weight of The Golden Gate Bridge, and the weight of The Golden Gate Bridge is 1,920,000 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 0.8050 megatonnes. 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 2,000,000 times as heavy as a Raindrop
In other words, the weight of a Raindrop is 0.000000500 times 0.000000420 megatonnes.(a.k.a. drop, a.k.a. droplet) (average)
The weight of a raindrop depends heavily on the type of weather, but averages about 0.000000000000200 megatonnes. The familiar teardrop shape of a raindrop is actually an optical illusion, caused by the reflection of the light and the motion of the drop.
It's about 0.00000007 times as heavy as The Great Pyramid of Giza
In other words, 0.000000420 megatonnes is 0.0000000710 times the weight of The Great Pyramid of Giza, and the weight of The Great Pyramid of Giza is 14,000,000 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 5.90 megatonnes. The 2,300,000 stones used in the construction of the pyramid weighed an average 0.00000230 megatonnes and were quarried from distances of up to 805 km (500 mi) away.
It's about 20,000,000 times as heavy as a Grain of Rice
In other words, the weight of a Grain of Rice is 0.0000000500 times 0.000000420 megatonnes.(conventional; US; long-, medium-, and short-gran varieties; uncooked)
With great differences in variety, the average among a sampling of common short-, medium- and long-grain rices finds that a single grain weighs about 0.0000000000000210 megatonnes before cooking. A staple through most of human history, archaeological evidence indicates that the earliest rice cultivation was about 11,500 years ago.
It's about 95,000,000 times as heavy as a Grain of Sand
In other words, the weight of a Grain of Sand is 0.0000000110 times 0.000000420 megatonnes.(medium grain)
With tremendous variety in the size of grain and the component material, grains of sand weigh an average of 0.00000000000000440 megatonnes. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 15.10 m (49.55 ft) in height.
It's about 100,000,000 times as heavy as a Sesame Seed
In other words, 0.000000420 megatonnes is 115,000,000 times the weight of a Sesame Seed, and the weight of a Sesame Seed is 0.00000000870 times that amount.(Sesamum indicum)
A sesame seed weighs approximately 0.000000000000003640 megatonnes. The McDonald's Big Mac sandwich, which is well-known for its sesame seed top bun, accounts for the consumption of an estimated 0.000002010 megatonnes of sesame seeds each day.