It's about 6,000,000,000 times as heavy as a liter of Water
In other words, 5.90 megatonnes is 5,899,835,000 times the weight of a liter of Water, and the weight of a liter of Water is 0.00000000016949630 times that amount.(fresh; 4° C / 39.2° F; maximum density)
Contrary to popular belief, 1 liter (0.0.264172052358148 gal) of water at 4° C / 39.2° F (its point of maximum density) weighs 0.0000000010000280 megatonnes rather than 1 kg exactly. The total volume of water on the planet Earth is about 13,590,000,000,000,000,000 (13.59 quntillion) L (3,590,000,000,000,000,000 gallons).
It's about 4,500,000,000 times as heavy as a Human Brain
In other words, 5.90 megatonnes is 4,370,000,000 times the weight of a Human Brain, and the weight of a Human Brain is 0.0000000002290 times that amount.(adult)
The average weight of an adult human brain is between 0.000000001350 megatonnes. In humans and primates, sight and vision utilize about 30 different parts of the brain which together account for about half of the brain's size.
It's about 2,500,000,000 times as heavy as a Chihuahua
In other words, 5.90 megatonnes is 2,620,000,000 times the weight of a Chihuahua, and the weight of a Chihuahua is 0.0000000003820 times that amount.(a.k.a. Chihuahue(o) (FCI standard)
The F&d&ration Cynologique Internationale (FCI) calls for Chihuahuas to weigh about 0.000000002250 megatonnes. Relative to their body sizes, Chihuahuas have the largest brain size of any dog breed.
It's about 2,000,000,000 times as heavy as a Brick
In other words, the weight of a Brick is 0.000000000500 times 5.90 megatonnes.(Standard, traditional face brick - 1,900 cu. cm (120 cu. in))
A standard, traditional face brick weighs an average of 0.00000000290 megatonnes. The steeple of the Church of St. Martin in Landshut, Germany is said to be the tallest brick tower in the world at a height of 130.6 m (428.5 ft) and was constructed using an estimated 650,000 bricks.
It's about 1,000,000,000 times as heavy as a Gallon of Paint
It's about 1,000,000,000 times as heavy as a Cat
In other words, the weight of a Cat is 0.000000001000 times 5.90 megatonnes.(Felis catus) (Domestic; healthy weight)
The average domestic cat should weigh about 0.00000000500 megatonnes. Cats are known for their righting reflex, which allows them to land on their feet and survive falls from heights of 1 m up to about 21 m.
It's about 850,000,000 times as heavy as a Bowling Ball
In other words, 5.90 megatonnes is 867,151,565 times the weight of a Bowling Ball, and the weight of a Bowling Ball is 0.000000001153200940 times that amount.(most common selection among male bowlers)
With an allowable range of 0.000000004989516070 megatonnes, the most-preferred bowling ball weight among adult, male bowlers is 0.000000006803885550 megatonnes. Because regulation balls measure the same diameter irrespective of their weight, ball density varies by size and balls weighing less than about 0.00000000500 megatonnes will float in water.