211131221 has 4 divisors (see below), whose sum is σ = 241292832. Its totient is φ = 180969612.

The previous prime is 211131203. The next prime is 211131227. The reversal of 211131221 is 122131112.

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 a cyclic number.

It is not a de Polignac number, because 211131221 - 2⁶ = 211131157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 211131196 and 211131205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211131227) 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, 15080795 + ... + 15080808.

It is an arithmetic number, because the mean of its divisors is an integer number (60323208).

Almost surely, 2^211131221 is an apocalyptic number.

It is an amenable number.

211131221 is a deficient number, since it is larger than the sum of its proper divisors (30161611).

211131221 is an equidigital number, since it uses as much as digits as its factorization.

211131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30161610.

The product of its digits is 24, while the sum is 14.

The square root of 211131221 is about 14530.3551573938. The cubic root of 211131221 is about 595.4575686091.

Adding to 211131221 its reverse (122131112), we get a palindrome (333262333).

The spelling of 211131221 in words is "two hundred eleven million, one hundred thirty-one thousand, two hundred twenty-one".