258 Jean-Marie De Koninck
390 625 (= 58)
the third number n 1 whose sum of digits is equal to
4

n (see the number
2 401).
392 113
the
22nd
(and the largest known) prime number pk such that p1p2 . . . pk + 1 is
prime (see the number 379).
392 448
(=28
· 3 · 7 · 73)
the sixth Erd˝ os-Nicolas number (see the number 2 016).
393 216
the 18th Granville number (see the number 126).
396 733
the smallest prime number p such that p+100 is prime and such that each num-
ber between p and p + 100 is composite (see the numbers 370 261, 378 043 979,
4 758 958 741 and 22 439 962 446 379 651, as well as the table given at the number
139).
397 612
the largest known number n = [d1, d2, . . . , dr] such that n = d1r
d
+ d2r−1
d
+ . . . +
dr1
d
: here 397 612 =
32
+
91
+
76
+
67
+
19
+
23;
the only other known number
satisfying this property is 48 625, an observation due to Patrick De Geest.
404 851
the smallest prime number p such that p + 90 is prime and such that each
number between p and p + 90 is composite (see the number 139).
409 113
the value of 1! + 2! + . . . + 9!.
409 619
the eighth Hamilton number (see the number 923).
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