212221021 has 4 divisors (see below), whose sum is σ = 212268700. Its totient is φ = 212173344.

The previous prime is 212221019. The next prime is 212221033. The reversal of 212221021 is 120122212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46172025 + 166048996 = 6795^2 + 12886^2 .

It is a cyclic number.

It is not a de Polignac number, because 212221021 - 2¹ = 212221019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212220992 and 212221010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212221721) 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, 16386 + ... + 26323.

It is an arithmetic number, because the mean of its divisors is an integer number (53067175).

Almost surely, 2^212221021 is an apocalyptic number.

It is an amenable number.

212221021 is a deficient number, since it is larger than the sum of its proper divisors (47679).

212221021 is an equidigital number, since it uses as much as digits as its factorization.

212221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47678.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 212221021 is about 14567.8076936786. The cubic root of 212221021 is about 596.4803390536.

Adding to 212221021 its reverse (120122212), we get a palindrome (332343233).

The spelling of 212221021 in words is "two hundred twelve million, two hundred twenty-one thousand, twenty-one".