211221210 has 64 divisors (see below), whose sum is σ = 529545600. Its totient is φ = 53851392.

The previous prime is 211221169. The next prime is 211221229. The reversal of 211221210 is 12122112.

It is a super-2 number, since 2×211221210² = 89228799107728200, which contains 22 as substring.

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 31 ways as a sum of consecutive naturals, for example, 91956 + ... + 94224.

It is an arithmetic number, because the mean of its divisors is an integer number (8274150).

Almost surely, 2^211221210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 211221210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (264772800).

211221210 is an abundant number, since it is smaller than the sum of its proper divisors (318324390).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

211221210 is a wasteful number, since it uses less digits than its factorization.

211221210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2415.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 211221210 is about 14533.4514138934. The cubic root of 211221210 is about 595.5421558462.

Adding to 211221210 its reverse (12122112), we get a palindrome (223343322).

The spelling of 211221210 in words is "two hundred eleven million, two hundred twenty-one thousand, two hundred ten".