In this sequence, it should be 27, not 28 (28 is not divisible by 3)
I would say 21, because it is not an even number like the rest are.
The median is 27.
22, 24, 25, 26, 28
Number of neutrons = mass number - atomic number = 49 - 21 = 28
27
, 21, 22, 24, 25, 26, 27, 28
27
No number has all of the same factors as another number. 21, 22, 23, 24, 25, 26, 27, 28 and 29 have 1 in common. 21 and 28 share 1 and 7. 22, 24, 26, and 28 share 1 and 2. 24 and 28 share 1, 2 and 4
21 and 28 are composite.
20 21 22 24 25 26 27 28 30
When figuring out what number goes both into 21 and 28, you should look at the factor paris. 21: 1 x 21, 3 x 7 28: 1, 28, 2 x 14, 4 x 7 7 goes into both 21 and 28.
Bandstand - 1952 24-21 was released on: USA: 28 March 1981