282 Jean-Marie De Koninck
2 199 978
the eighth number which is not a palindrome, but which divides the number
obtained by reversing its digits (see the number 1 089).
2 230 271
the seventh solution of σ2(n) = σ2(n + 2) (see the number 1 079).
2 424 833
the smallest prime factor of the Fermat number F9 =
229
+ 1, whose complete
factorization is given by
F9 = 2424833 · 7455602825647884208337395736200454918783366342657 · P99.
2 469 601 (=
192
· 6841)
the third 18-hyperperfect number (see the number 1 333).
2 481 757
the second prime number p such that
23p−1
1 (mod
p2);
see the number
13.
2 500 704
the third and largest known dihedral 3-perfect number (see the number 5 472).
2 562 624
the smallest number which can be written as the sum of three distinct cubes
in eight distinct ways:
2 562 624 =
83
+
363
+
1363
=
83
+
643
+
1323
=
123
+
1003
+
1163
=
173
+
463
+
1353
=
303
+
1033
+
1133
=
363
+
603
+
1323
=
513
+
853
+
1223
=
693
+
723
+
1233
(see the number 1 009).
2 568 226
the third even number n for which
2n
2 (mod n); see the number 161 038.
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