Those Fascinating Numbers 283
2 590 623
the first of the three smallest consecutive numbers each of which is divisible
by a fifth power: here 2 590 623 =
35
· 7 · 1523, 2 590 624 =
25
· 73 · 1109 and
2 590 625 =
55
· 829 (see the number 1 375).
2 646 798
the ninth (and possibly the largest) number n 9 such that n =
∑r
i=1
di, i where
d1, . . . , dr stand for the digits of n: here 2 646 798 = 21 +62 +43 +64 +75 +96 +87
(see the number 175).
2 657 333
the third number which can be written in two distinct ways as the sum of
two co-prime numbers each with an index of composition 5: 2 657 333 =
27 + 312 · 5 = 55 + 215 · 34, each of these last four numbers having as index of
composition 7, 5.46252, 5 and 8.25538 respectively (see the number 371 549).
2 674 440
the
14th
Catalan number (see the number 14).
2 677 889
the smallest number of persistence 8 (see the number 679).
2 702 765
the 12th Euler number (see the number 272).
2 704 900
the fourth multiple of 100 such that the following 100 numbers include ex-
actly 17 prime numbers, namely 2704901, 2704903, 2704907, 2704909, 2704927,
2704931, 2704937, 2704939, 2704943, 2704957, 2704963, 2704969, 2704979,
2704981, 2704987, 2704993, 2704997 (see the number 400).
2 718 281
the third prime number built from the first digits of the decimal expansion of
the Euler number e (see the number 271).
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