221011221 has 4 divisors (see below), whose sum is σ = 294681632. Its totient is φ = 147340812.

The previous prime is 221011201. The next prime is 221011243. The reversal of 221011221 is 122110122.

221011221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 221011221 - 2⁶ = 221011157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 221011197 and 221011206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221011201) 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, 36835201 + ... + 36835206.

It is an arithmetic number, because the mean of its divisors is an integer number (73670408).

Almost surely, 2^221011221 is an apocalyptic number.

It is an amenable number.

221011221 is a deficient number, since it is larger than the sum of its proper divisors (73670411).

221011221 is an equidigital number, since it uses as much as digits as its factorization.

221011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73670410.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 221011221 is about 14866.4461455992. The cubic root of 221011221 is about 604.6045919368.

Adding to 221011221 its reverse (122110122), we get a palindrome (343121343).

It can be divided in two parts, 2210 and 11221, that added together give a palindrome (13431).

The spelling of 221011221 in words is "two hundred twenty-one million, eleven thousand, two hundred twenty-one".