211221205 has 8 divisors (see below), whose sum is σ = 272962872. Its totient is φ = 155978688.

The previous prime is 211221169. The next prime is 211221229. The reversal of 211221205 is 502122112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2187441 + 209033764 = 1479^2 + 14458^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 211221205 - 2⁷ = 211221077 is a prime.

It is a super-2 number, since 2×211221205² = 89228794883304050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1624714 + ... + 1624843.

It is an arithmetic number, because the mean of its divisors is an integer number (34120359).

Almost surely, 2^211221205 is an apocalyptic number.

It is an amenable number.

211221205 is a deficient number, since it is larger than the sum of its proper divisors (61741667).

211221205 is a wasteful number, since it uses less digits than its factorization.

211221205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3249575.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 211221205 is about 14533.4512418764. The cubic root of 211221205 is about 595.5421511470.

Adding to 211221205 its reverse (502122112), we get a palindrome (713343317).

The spelling of 211221205 in words is "two hundred eleven million, two hundred twenty-one thousand, two hundred five".