221100221 has 8 divisors (see below), whose sum is σ = 222661560. Its totient is φ = 219543552.

The previous prime is 221100203. The next prime is 221100227. The reversal of 221100221 is 122001122.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 11256025 + 209844196 = 3355^2 + 14486^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221100221 - 2⁶ = 221100157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221100227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198815 + ... + 199923.

It is an arithmetic number, because the mean of its divisors is an integer number (27832695).

Almost surely, 2^221100221 is an apocalyptic number.

It is an amenable number.

221100221 is a deficient number, since it is larger than the sum of its proper divisors (1561339).

221100221 is a wasteful number, since it uses less digits than its factorization.

221100221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2335.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 221100221 is about 14869.4391622549. The cubic root of 221100221 is about 604.6857380239.

Adding to 221100221 its reverse (122001122), we get a palindrome (343101343).

Subtracting from 221100221 its reverse (122001122), we obtain a palindrome (99099099).

The spelling of 221100221 in words is "two hundred twenty-one million, one hundred thousand, two hundred twenty-one".