• 4242 = 179776 is the smallest square that contains exactly three digits '7'.
• 424 can be written using four 4's:
424 is nontrivially palindromic in base 10.
424 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.
It is a tau number, because it is divible by the number of its divisors (8).
It is a nude number because it is divisible by every one of its digits.
424 is an undulating number in base 10.
It is a plaindrome in base 7, base 11, base 13 and base 14.
It is a nialpdrome in base 8 and base 9.
It is a zygodrome in base 7.
It is a self number, because there is not a number n which added to its sum of digits gives 424.
It is an amenable number.
424 is a wasteful number, since it uses less digits than its factorization.
424 is an evil number, because the sum of its binary digits is even.
The square root of 424 is about 20.5912602820. The cubic root of 424 is about 7.5125715084.
Adding to 424 its sum of digits (10), we get a palindrome (434).
Subtracting from 424 its sum of digits (10), we obtain a palindrome (414).