21102211209 has 4 divisors (see below), whose sum is σ = 28136281616. Its totient is φ = 14068140804.

The previous prime is 21102211187. The next prime is 21102211213. The reversal of 21102211209 is 90211220112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21102211209 - 2⁸ = 21102210953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21102211219) 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, 3517035199 + ... + 3517035204.

It is an arithmetic number, because the mean of its divisors is an integer number (7034070404).

Almost surely, 2^21102211209 is an apocalyptic number.

It is an amenable number.

21102211209 is a deficient number, since it is larger than the sum of its proper divisors (7034070407).

21102211209 is an equidigital number, since it uses as much as digits as its factorization.

21102211209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7034070406.

The product of its (nonzero) digits is 144, while the sum is 21.

The spelling of 21102211209 in words is "twenty-one billion, one hundred two million, two hundred eleven thousand, two hundred nine".