211231221 has 16 divisors (see below), whose sum is σ = 289621248. Its totient is φ = 136857600.

The previous prime is 211231219. The next prime is 211231271. The reversal of 211231221 is 122132112.

It is not a de Polignac number, because 211231221 - 2¹ = 211231219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 211231221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211231271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30165 + ... + 36501.

It is an arithmetic number, because the mean of its divisors is an integer number (18101328).

Almost surely, 2^211231221 is an apocalyptic number.

It is an amenable number.

211231221 is a deficient number, since it is larger than the sum of its proper divisors (78390027).

211231221 is a wasteful number, since it uses less digits than its factorization.

211231221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6652.

The product of its digits is 48, while the sum is 15.

The square root of 211231221 is about 14533.7958221519. The cubic root of 211231221 is about 595.5515644315.

Adding to 211231221 its reverse (122132112), we get a palindrome (333363333).

It can be divided in two parts, 2112 and 31221, that added together give a palindrome (33333).

The spelling of 211231221 in words is "two hundred eleven million, two hundred thirty-one thousand, two hundred twenty-one".