21204102111 has 4 divisors (see below), whose sum is σ = 28272136152. Its totient is φ = 14136068072.

The previous prime is 21204102077. The next prime is 21204102133. The reversal of 21204102111 is 11120140212.

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 21204102111 - 2⁷ = 21204101983 is a prime.

It is a super-2 number, since 2×21204102111² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204102181) 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, 3534017016 + ... + 3534017021.

It is an arithmetic number, because the mean of its divisors is an integer number (7068034038).

Almost surely, 2^21204102111 is an apocalyptic number.

21204102111 is a deficient number, since it is larger than the sum of its proper divisors (7068034041).

21204102111 is an equidigital number, since it uses as much as digits as its factorization.

21204102111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7068034040.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21204102111 its reverse (11120140212), we get a palindrome (32324242323).

The spelling of 21204102111 in words is "twenty-one billion, two hundred four million, one hundred two thousand, one hundred eleven".