4221 has 12 divisors (see below), whose sum is σ = 7072.
Its totient is φ = 2376.
The previous prime is 4219. The next prime is 4229. The reversal of 4221 is 1224.
4221 is nontrivially palindromic in base 6.
It is not a de Polignac number, because 4221 - 21 = 4219 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9).
It is a Duffinian number.
4221 is an undulating number in base 6.
It is a Curzon number.
It is a plaindrome in base 14.
It is a nialpdrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (4229) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30 + ... + 96.
24221 is an apocalyptic number.
It is an amenable number.
4221 is a deficient number, since it is larger than the sum of its proper divisors (2851).
4221 is a wasteful number, since it uses less digits than its factorization.
4221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 80 (or 77 counting only the distinct ones).
The product of its digits is 16, while the sum is 9.
The square root of 4221 is about 64.9692234831.
The cubic root of 4221 is about 16.1611322443.
Adding to 4221 its reverse (1224), we get a palindrome (5445).
It can be divided in two parts, 4 and 221, that added together give a square (225 = 152).
The spelling of 4221 in words is "four thousand, two hundred twenty-one", and thus it is an iban number.