338 Jean-Marie De Koninck

1 082 640 256

• the

22nd

dihedral perfect number (see the number 130).

1 111 112 112

• the sixth insolite number (see the number 111).

1 111 211 136

• the seventh insolite number (see the number 111).

1 116 122 112

• the eighth insolite number (see the number 111).

1 152 597 606

• the fourth number which is not the square of a prime number, but which

can be written as the sum of the squares of some of its prime factors: here

1 152 597 606 = 2 · 3 · 5741 · 33461 = 22 + 57412 + 334612 (see the number 870).

1 178 491 680

• the

12th

number n such that φ(n) + σ(n) = 4n (see the number 23 760).

1 211 162 112

• the ninth insolite number (see the number 111).

1 214 251 009

• the smallest prime factor of F15 =

2215

+ 1, whose partial factorization is given

by

F15 = 1214251009 · 2327042503868417

·168768817029516972383024127016961 · C9808.

1 220 640 625 (=

56

· 78121)

• the second 4-hyperperfect number (see the number 1 950 625).

1 268 860 318

• the second number n such that n2 + 1 is powerful (see the number 682): here

1 268 860 3182 + 1 = 53 · 172 · 612 · 1094412.