Numbers 66,000s

A page of the Numeropedia - the Special Encyclopedia of Numbers

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66,066

[Math.]  Both numbers 363 and the 363rd triangluar number (66,066) are palindromic.

66,105

[Math.]  661052 = 4,369,871,025, a square number using each of 10 digits 0-9 once. (The 45th of 87 such numbers).

66,276

[Math.]  662762 = 4,392,508,176, a square number using each of 10 digits 0-9 once. (The 46th of 87 such numbers).

663nn

[Zip]  No such U.S. Postal Zip Codes.

66,420

[Math.]  Two consecutive sums of consecutive numbers:

1600+1601+…+1640 = 1641+1642+…+1680 = 66,420.

66,430

[Math.]  Sum 1+91+92+93+94+95 = 66,430 is a triangular number = 1+2+…+363+364.

66,665

[Math.]  Repeatedly inserting numbers 42 between the digits 4 and 2 in the square number 4225 = 652 yields other squares 442225 = 6652, 44422225 = 66652, 4444222225 = 666652, 444442222225 = 6666652

[Math.]  Square of numbers of similar pattern xxy, where y = x–1.

* 1102 = 012,100 & 012+100 = 112 = 110+2.

* 3322 = 110,224 & 110+224 = 334 = 332+2.

Similarly, 3…322 = 1…102…24 & 1…10+2…24 = 3…34 = 3…32+2.

* 4432 = 196,249 & 196+249 = 445 = 443+2

* 6652 = 442,225 & 442+225 = 667 = 665+2.

Similarly, 6…652 = 4…422…25 & 4…42+2…25 = 6…67 = 6…65+2.

66,6652 = 4,444,222,225 & 44,442+22,225 = 66,667 = 66,665+2.

* 7762 = 602,176 & 602+176 = 778 = 776+2.

66,666.333332...

[Math.]

401/2 = 6.32…

44001/2 = 66.332…

4440001/2 = 666.3332…

444400001/2 = 6666.33332…

44444000001/2 = 66666.333332…

4444440000001/2 = 66666.3333332…

444444400000001/2 = 6666666.33333332…

66,667

[Math.]  33333,66667,00000 = 33,3333+66,6673+000003 and

33333,66667,00001 = 33,3333+66,6673+000013.

333,340,000,066,667 = 333343+000003+666673. (Generalizable)

[Math.]  13,333,466,667 = 133,3342–66,6672 = (133334+66667)×66667, where 133334 = 66667×2.

[Math.]  Repeatedly inserting numbers 48 in the middle of the square number 49 yields other squares 4489 = 672, 444889 = 6672, 44448889 = 66672, 4444488889 = 666672

[Math.]  777762 = 6,049,106,176 and 60491+06176 = 66667.

[Zip]  U.S. Postal Zip Code: Topeka, Kansas 66667.

66,668

[Math.]  3,333,466,668 = 66,6682–33,3342 = (33334+66668)×33334, where 66668 = 33334×2.

66,863

[Math.]  The 6663rd prime number is 66,863.

66,928

[Math.]  A pair of amicable numbers (66928, 66992).

66,992

[Math.]  A pair of amicable numbers (66928, 66992).

66nnn

[Zip]  U.S. Postal Zip Codes of Kansas: 66nnn-67nnn.

66661, 66663, 66664, 66666, 66667, 6666866669

66670, 66671, 66672, 66674 & 66675

[Math.]

 66×64 = 4224 66×67 = 4422 66×68 = 4488 66×69 = 4554 66×74 = 4884

...

 66666×66661 = 4444022226 66666×66669 = 4444555554 66666×66663 = 4444155558 66666×66670 = 4444622220 66666×66664 = 4444222224 66666×66671 = 4444688886 66666×66666 = 4444355556 66666×66672 = 4444755552 66666×66667 = 4444422222 66666×66674 = 4444888884 66666×66668 = 4444488888 66666×66675 = 4444955550

… (generalizable pattern) …