Those Fascinating Numbers 385
48 698 490 414 981 559 698
the second number which is not a fourth power, but which can be written as
the sum of the fourth powers of some of its prime factors: here
48 698 490 414 981 559 698 = 2 ·
34
· 7 · 13 · 17 · 157 · 83537 · 14816023
=
24
+
174
+
835374;
the smallest number satisfying this property is 107 827 277 891 825 604 (see the
number 870).
53 861 511 409 489 970 176 (=
9410)
the third number n 1 whose sum of digits is equal to
10

n (see the number
13 744 803 133 596 058 624).
73 742 412 689 492 826 049 (=
9710)
the fourth number n 1 whose sum of digits is equal to
10

n (see the number
13 744 803 133 596 058 624).
89 726 156 799 336 363 541
the largest left truncatable prime number whose last digit is 1 (Gerry Myerson,
West Coast Number Theory Problems, 1999); see the number 73 939 133.
92 801 587 319 328 411 133
the
19th
horse number (see the number 13).
99 999 999 999 999 999 989
the largest 20 digit prime number.
100 000 000 000 000 000 039
the smallest 21 digit prime number.
154 345 556 085 770 649 600 (= 215 · 35 · 52 · 72 · 11 · 13 · 17 · 19 · 31 · 43 · 257)
the smallest 6-perfect number, that is a number n such that σ(n) = 6n (see the
number 6); it is believed that there are no more than 245 such numbers (see
R.K. Guy [104]).
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