7777

7777 = 7 x 11 x 101. It is a palindrome with exactly three distinct palindromic prime factors (A046409).

7777 has the representation 6⁵ + 1 (A062394). It is 100001 (palindromic) in base 6 (A029963 and A033043).

7777 divides 36⁵ - 1.

7777 is a number that is the sum of two positive fifth powers (A003347 and A004842).

7777 is a Kaprekar number (A006886).

Source: OEIS