Numbers 21,000,000s

A page of the Numeropedia - the Special Encyclopedia of Numbers

21,000,00022,000,00023,000,000 – 24,000,000

25,000,00026,000,00027,000,00028,000,00029,000,000

All Numbers  & [1M] & [10M- [20M] - [30M] - [40M] - [50M] - [60M] - [70M] - [80M] - [90M] &  [100M]

1  - 10 - 100  - 1000 - 10,000 - 100,000 - 1M - 10M - 100M1B10B - 100B - 1T - 10T - 100T - 1Q ...

21,356,784

[Math.]  85,427,136 = 2×42,713,568 = 4×21,356,784 = 6×14,237,856, all 3 factorizations using 3 permutations of the number itself (digit 9 is not used).

21,448,630

[Math.]  A pair of amicable numbers (21448630, 23030090).

21,457,192

[Math.]  A pair of amicable numbers (20014808, 21457192).

21,531,778

[Math.]  A Markov number.

21,600,000

[Math.]  21,600,000 = 33×44×55.

21,678,336

[Math.]  Sum of the first 96 cube numbers:

13+23+…+953+963 = 21,678,336 = (1+2+…+95+96)2 = 46562.

21,782,178 & 21,999,978

[Math.]

(*)   8712 = 2178×4 & 8712×2178 = 18,974,736 = 43562 (= 664)

8712…8712 = 2178…2178×4 & 8712…8712×2178…2178 = 4356…43562.

(**)   87912 = 21978×4 & 21978×87912 = 1,932,129,936 = 439562

87912…87912 = 21978…21978×4 &

21978…21978×87912…87912 = 43956…439562.

(***)   87999912 = 21999978×4 & 21999978×87999912 = 439999562

87999912…87999912 = 21999978…21999978×4 &

21999978…21999978×87999912…87999912 = 43999956…439999562.

(****)   879…912 = 219…978×4 & 219…978×879…912 = 439…9562

879…912…879…912 = 219…978…219…978×4 &

219...978...219...978×879...912...879...912 = 439...956...439...9562.

...

xy,abc,def

[Math.]  For any xy = 10 to 99, there are always six 6-digit numbers abc,edf such that the sum (xy+abc,def) is equal to one of 6 digit-rotations of 142,857 and the number xy,abc,def is a multiple of 142,857.

For any xy = 10 to 99, there are always twelve 6-digit numbers abc,edf such that the sum (xy+abc,def) is equal to one of 12 digit-rotations of 076,923 or 153,846 and the number xy,abc,def is a multiple of 76,923.