21221111211 has 8 divisors (see below), whose sum is σ = 28296956880. Its totient is φ = 14146336512.

The previous prime is 21221111173. The next prime is 21221111273. The reversal of 21221111211 is 11211112212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21221111211 - 2⁹ = 21221110699 is a prime.

It is a super-2 number, since 2×21221111211² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21221111281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 220306 + ... + 301623.

It is an arithmetic number, because the mean of its divisors is an integer number (3537119610).

Almost surely, 2^21221111211 is an apocalyptic number.

21221111211 is a deficient number, since it is larger than the sum of its proper divisors (7075845669).

21221111211 is a wasteful number, since it uses less digits than its factorization.

21221111211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 535485.

The product of its digits is 16, while the sum is 15.

Adding to 21221111211 its reverse (11211112212), we get a palindrome (32432223423).

The spelling of 21221111211 in words is "twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, two hundred eleven".