211220221 has 4 divisors (see below), whose sum is σ = 211606912. Its totient is φ = 210833532.

The previous prime is 211220153. The next prime is 211220231. The reversal of 211220221 is 122022112.

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-211220221 is a prime.

It is a super-2 number, since 2×211220221² = 89227963518577682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211220231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 192525 + ... + 193618.

It is an arithmetic number, because the mean of its divisors is an integer number (52901728).

Almost surely, 2^211220221 is an apocalyptic number.

It is an amenable number.

211220221 is a deficient number, since it is larger than the sum of its proper divisors (386691).

211220221 is an equidigital number, since it uses as much as digits as its factorization.

211220221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386690.

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

The square root of 211220221 is about 14533.4173889007. The cubic root of 211220221 is about 595.5412263434.

Adding to 211220221 its reverse (122022112), we get a palindrome (333242333).

The spelling of 211220221 in words is "two hundred eleven million, two hundred twenty thousand, two hundred twenty-one".