212331221 has 4 divisors (see below), whose sum is σ = 213081792. Its totient is φ = 211580652.

The previous prime is 212331211. The next prime is 212331233. The reversal of 212331221 is 122133212.

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 a de Polignac number, because none of the positive numbers 2^k-212331221 is a prime.

It is a super-2 number, since 2×212331221² = 90169094822701682, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 212331221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212331211) 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 3 ways as a sum of consecutive naturals, for example, 374861 + ... + 375426.

It is an arithmetic number, because the mean of its divisors is an integer number (53270448).

Almost surely, 2^212331221 is an apocalyptic number.

It is an amenable number.

212331221 is a deficient number, since it is larger than the sum of its proper divisors (750571).

212331221 is an equidigital number, since it uses as much as digits as its factorization.

212331221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 750570.

The product of its digits is 144, while the sum is 17.

The square root of 212331221 is about 14571.5895152176. The cubic root of 212331221 is about 596.5835659610.

Adding to 212331221 its reverse (122133212), we get a palindrome (334464433).

The spelling of 212331221 in words is "two hundred twelve million, three hundred thirty-one thousand, two hundred twenty-one".