212031221 has 4 divisors (see below), whose sum is σ = 212063712. Its totient is φ = 211998732.

The previous prime is 212031173. The next prime is 212031251. The reversal of 212031221 is 122130212.

It is a happy number.

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-212031221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212031196 and 212031205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212031251) 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, 2681 + ... + 20766.

It is an arithmetic number, because the mean of its divisors is an integer number (53015928).

Almost surely, 2^212031221 is an apocalyptic number.

It is an amenable number.

212031221 is a deficient number, since it is larger than the sum of its proper divisors (32491).

212031221 is an equidigital number, since it uses as much as digits as its factorization.

212031221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32490.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 212031221 is about 14561.2918726327. The cubic root of 212031221 is about 596.3024651638.

Adding to 212031221 its reverse (122130212), we get a palindrome (334161433).

The spelling of 212031221 in words is "two hundred twelve million, thirty-one thousand, two hundred twenty-one".