21210211 has 6 divisors (see below), whose sum is σ = 23313836. Its totient is φ = 19281900.

The previous prime is 21210197. The next prime is 21210221. The reversal of 21210211 is 11201212.

It is not a de Polignac number, because 21210211 - 2⁵ = 21210179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87525 + ... + 87766.

Almost surely, 2^21210211 is an apocalyptic number.

21210211 is a deficient number, since it is larger than the sum of its proper divisors (2103625).

21210211 is a wasteful number, since it uses less digits than its factorization.

21210211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175313 (or 175302 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 21210211 is about 4605.4544835445. The cubic root of 21210211 is about 276.8099283850.

Adding to 21210211 its reverse (11201212), we get a palindrome (32411423).

The spelling of 21210211 in words is "twenty-one million, two hundred ten thousand, two hundred eleven".