211020221 has 4 divisors (see below), whose sum is σ = 215927712. Its totient is φ = 206112732.

The previous prime is 211020163. The next prime is 211020233. The reversal of 211020221 is 122020112.

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-211020221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211020241) 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, 2453681 + ... + 2453766.

It is an arithmetic number, because the mean of its divisors is an integer number (53981928).

Almost surely, 2^211020221 is an apocalyptic number.

It is an amenable number.

211020221 is a deficient number, since it is larger than the sum of its proper divisors (4907491).

211020221 is an equidigital number, since it uses as much as digits as its factorization.

211020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4907490.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 211020221 is about 14526.5350651833. The cubic root of 211020221 is about 595.3531984829.

Adding to 211020221 its reverse (122020112), we get a palindrome (333040333).

The spelling of 211020221 in words is "two hundred eleven million, twenty thousand, two hundred twenty-one".