4221221 has 4 divisors (see below), whose sum is σ = 4225452. Its totient is φ = 4216992.

The previous prime is 4221209. The next prime is 4221223. The reversal of 4221221 is 1221224.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 3556996 + 664225 = 1886^2 + 815^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4221221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 4221196 and 4221205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4221223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 305 + ... + 2921.

It is an arithmetic number, because the mean of its divisors is an integer number (1056363).

Almost surely, 2^4221221 is an apocalyptic number.

It is an amenable number.

4221221 is a deficient number, since it is larger than the sum of its proper divisors (4231).

4221221 is a wasteful number, since it uses less digits than its factorization.

4221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4230.

The product of its digits is 64, while the sum is 14.

The square root of 4221221 is about 2054.5610236739. The cubic root of 4221221 is about 161.6141429025.

Adding to 4221221 its reverse (1221224), we get a palindrome (5442445).

The spelling of 4221221 in words is "four million, two hundred twenty-one thousand, two hundred twenty-one".