A261072 Divisors of 1234567890987654321.

1, 3, 7, 9, 19, 21, 57, 63, 133, 171, 399, 1197, 928163, 2784489, 6497141, 8353467, 17635097, 19491423, 52905291, 58474269, 123445679, 158715873, 370337037, 1111011111, 1111211111, 3333633333, 7778477777, 10000899999, 21113011109

Offset: 1

Author

Ilya Gutkovskiy, Aug 08 2015

Keywords

• nonn
• easy
• fini
• full

Comments

1234567890987654321 = A057139(10) is a palindrome with 48 divisors. See the link with all divisors.

From Wolfdieter Lang, Aug 22 2015: (Start)

The palindromes of this sequence are 1, 3, 7, 9, 171, 1234567890987654321.

1234567890987654321 = 1111011111 * 1111211111 (observed by Jon E. Schoenfield).

The palindromic divisors of 1111011111 are 1, 3, 7, 9 and 171. The only palindromic divisor of 1111211111 is 1. Therefore, of the six palindromes of this sequence only 1234567890987654321 cannot be obtained from the product of the palindromic divisors of 1111011111 with those of 1111211111. (End)

Links

• Ilya Gutkovskiy, Table of n, a(n) for n = 1..48
• Eric Weisstein's World of Mathematics, Divisor.
• Eric Weisstein's World of Mathematics, Palindromic Number.

Crossrefs

Cf. A057139, A261245.

Programs

Magma

[Divisors(1234567890987654321)]; // Vincenzo Librandi, Aug 09 2015

Maple

numtheory[divisors](1234567890987654321); # Wesley Ivan Hurt, Aug 11 2015

Mathematica

Divisors[1234567890987654321]

PARI

divisors(1234567890987654321) \\ Wesley Ivan Hurt, Aug 11 2015