• 441 can be written using four 4's:
441 has 9 divisors (see below), whose sum is σ = 741. Its totient is φ = 252.
The previous prime is 439. The next prime is 443. The reversal of 441 is 144.
The square root of 441 is 21.
It is a perfect power (a square), and thus also a powerful number.
441 is nontrivially palindromic in base 4.
441 is an esthetic number in base 4, because in such base its adjacent digits differ by 1.
It is an interprime number because it is at equal distance from previous prime (439) and next prime (443).
It is a tau number, because it is divible by the number of its divisors (9).
It is not a de Polignac number, because 441 - 21 = 439 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9).
It is an Ulam number.
It is a Curzon number.
It is a plaindrome in base 13 and base 14.
It is a nialpdrome in base 9 and base 10.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 441.
It is not an unprimeable number, because it can be changed into a prime (443) by changing a digit.
It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 60 + ... + 66.
441 is the 21-st square number.
441 is the 11-th centered octagonal number.
It is an amenable number.
441 is a deficient number, since it is larger than the sum of its proper divisors (300).
441 is a wasteful number, since it uses less digits than its factorization.
441 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 20 (or 10 counting only the distinct ones).
The product of its digits is 16, while the sum is 9.
The cubic root of 441 is about 7.6116626110.
Multiplying 441 by its product of digits (16), we get a square (7056 = 842).
Adding to 441 its reverse (144), we get a palindrome (585).
Multiplying 441 by its reverse (144), we get a square (63504 = 2522).
It can be divided in two parts, 44 and 1, that added together give a triangular number (45 = T9).
The spelling of 441 in words is "four hundred forty-one", and thus it is an aban number and an iban number.
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