21221021111 has 4 divisors (see below), whose sum is σ = 21408817872. Its totient is φ = 21033224352.

The previous prime is 21221021021. The next prime is 21221021113. The reversal of 21221021111 is 11112012212.

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 21221021111 - 2³⁴ = 4041151927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221021113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93898211 + ... + 93898436.

It is an arithmetic number, because the mean of its divisors is an integer number (5352204468).

Almost surely, 2^21221021111 is an apocalyptic number.

21221021111 is a deficient number, since it is larger than the sum of its proper divisors (187796761).

21221021111 is a wasteful number, since it uses less digits than its factorization.

21221021111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187796760.

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

Adding to 21221021111 its reverse (11112012212), we get a palindrome (32333033323).

The spelling of 21221021111 in words is "twenty-one billion, two hundred twenty-one million, twenty-one thousand, one hundred eleven".