221211221 has 32 divisors (see below), whose sum is σ = 286488576. Its totient is φ = 165816000.

The previous prime is 221211209. The next prime is 221211223. The reversal of 221211221 is 122112122.

It is not a de Polignac number, because 221211221 - 2¹⁸ = 220949077 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 221211196 and 221211205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221211223) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 234611 + ... + 235551.

It is an arithmetic number, because the mean of its divisors is an integer number (8952768).

Almost surely, 2^221211221 is an apocalyptic number.

It is an amenable number.

221211221 is a deficient number, since it is larger than the sum of its proper divisors (65277355).

221211221 is a wasteful number, since it uses less digits than its factorization.

221211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1073.

The product of its digits is 32, while the sum is 14.

The square root of 221211221 is about 14873.1711816949. The cubic root of 221211221 is about 604.7869121845.

Adding to 221211221 its reverse (122112122), we get a palindrome (343323343).

Subtracting from 221211221 its reverse (122112122), we obtain a palindrome (99099099).

The spelling of 221211221 in words is "two hundred twenty-one million, two hundred eleven thousand, two hundred twenty-one".