21002221111 has 4 divisors (see below), whose sum is σ = 21049630632. Its totient is φ = 20954811592.

The previous prime is 21002221099. The next prime is 21002221133. The reversal of 21002221111 is 11112220012.

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 21002221111 - 2¹⁹ = 21001696823 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21002221091 and 21002221100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002221411) 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, 23704096 + ... + 23704981.

It is an arithmetic number, because the mean of its divisors is an integer number (5262407658).

Almost surely, 2^21002221111 is an apocalyptic number.

21002221111 is a deficient number, since it is larger than the sum of its proper divisors (47409521).

21002221111 is an equidigital number, since it uses as much as digits as its factorization.

21002221111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47409520.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21002221111 its reverse (11112220012), we get a palindrome (32114441123).

The spelling of 21002221111 in words is "twenty-one billion, two million, two hundred twenty-one thousand, one hundred eleven".