21211101211 has 4 divisors (see below), whose sum is σ = 21212237800. Its totient is φ = 21209964624.

The previous prime is 21211101209. The next prime is 21211101257. The reversal of 21211101211 is 11210111212.

It is a happy number.

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 21211101211 - 2¹ = 21211101209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211101191 and 21211101200.

It is not an unprimeable number, because it can be changed into a prime (21211101281) 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, 539826 + ... + 577783.

It is an arithmetic number, because the mean of its divisors is an integer number (5303059450).

Almost surely, 2^21211101211 is an apocalyptic number.

21211101211 is a deficient number, since it is larger than the sum of its proper divisors (1136589).

21211101211 is a wasteful number, since it uses less digits than its factorization.

21211101211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1136588.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21211101211 its reverse (11210111212), we get a palindrome (32421212423).

The spelling of 21211101211 in words is "twenty-one billion, two hundred eleven million, one hundred one thousand, two hundred eleven".