21201211 has 4 divisors (see below), whose sum is σ = 21407152. Its totient is φ = 20995272.

The previous prime is 21201209. The next prime is 21201251. The reversal of 21201211 is 11210212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21201211 - 2¹ = 21201209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201251) 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 3 ways as a sum of consecutive naturals, for example, 102816 + ... + 103021.

It is an arithmetic number, because the mean of its divisors is an integer number (5351788).

Almost surely, 2^21201211 is an apocalyptic number.

21201211 is a deficient number, since it is larger than the sum of its proper divisors (205941).

21201211 is a wasteful number, since it uses less digits than its factorization.

21201211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205940.

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

The square root of 21201211 is about 4604.4772776071. The cubic root of 21201211 is about 276.7707704874.

Adding to 21201211 its reverse (11210212), we get a palindrome (32411423).

Subtracting from 21201211 its reverse (11210212), we obtain a palindrome (9990999).

It can be divided in two parts, 21201 and 211, that added together give a palindrome (21412).

The spelling of 21201211 in words is "twenty-one million, two hundred one thousand, two hundred eleven".