21012211211 has 4 divisors (see below), whose sum is σ = 21013401624. Its totient is φ = 21011020800.

The previous prime is 21012211201. The next prime is 21012211243. The reversal of 21012211211 is 11211221012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012211211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012211201) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 568325 + ... + 604166.

It is an arithmetic number, because the mean of its divisors is an integer number (5253350406).

Almost surely, 2^21012211211 is an apocalyptic number.

21012211211 is a deficient number, since it is larger than the sum of its proper divisors (1190413).

21012211211 is a wasteful number, since it uses less digits than its factorization.

21012211211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1190412.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21012211211 its reverse (11211221012), we get a palindrome (32223432223).

The spelling of 21012211211 in words is "twenty-one billion, twelve million, two hundred eleven thousand, two hundred eleven".