211111221 has 4 divisors (see below), whose sum is σ = 281481632. Its totient is φ = 140740812.

The previous prime is 211111193. The next prime is 211111231. The reversal of 211111221 is 122111112.

211111221 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 211111221 - 2⁵ = 211111189 is a prime.

It is a super-2 number, since 2×211111221² = 89135895264221682, which contains 22 as substring.

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 = 211111197 and 211111206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211111231) 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, 35185201 + ... + 35185206.

It is an arithmetic number, because the mean of its divisors is an integer number (70370408).

Almost surely, 2^211111221 is an apocalyptic number.

It is an amenable number.

211111221 is a deficient number, since it is larger than the sum of its proper divisors (70370411).

211111221 is an equidigital number, since it uses as much as digits as its factorization.

211111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70370410.

The product of its digits is 8, while the sum is 12.

The square root of 211111221 is about 14529.6669266711. Note that the first 3 decimals coincide. The cubic root of 211111221 is about 595.4387658832.

Adding to 211111221 its reverse (122111112), we get a palindrome (333222333).

The spelling of 211111221 in words is "two hundred eleven million, one hundred eleven thousand, two hundred twenty-one".