21202211209 has 4 divisors (see below), whose sum is σ = 21420790804. Its totient is φ = 20983631616.

The previous prime is 21202211189. The next prime is 21202211243. The reversal of 21202211209 is 90211220212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8569575184 + 12632636025 = 92572^2 + 112395^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202211209 - 2⁷ = 21202211081 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21202211209.

It is not an unprimeable number, because it can be changed into a prime (21202211609) 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, 109289652 + ... + 109289845.

It is an arithmetic number, because the mean of its divisors is an integer number (5355197701).

Almost surely, 2^21202211209 is an apocalyptic number.

It is an amenable number.

21202211209 is a deficient number, since it is larger than the sum of its proper divisors (218579595).

21202211209 is an equidigital number, since it uses as much as digits as its factorization.

21202211209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218579594.

The product of its (nonzero) digits is 288, while the sum is 22.

The spelling of 21202211209 in words is "twenty-one billion, two hundred two million, two hundred eleven thousand, two hundred nine".