21211022309 has 4 divisors (see below), whose sum is σ = 21662320704. Its totient is φ = 20759723916.

The previous prime is 21211022177. The next prime is 21211022311. The reversal of 21211022309 is 90322011212.

It is a happy number.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211022309 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211022909) 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, 225649127 + ... + 225649220.

It is an arithmetic number, because the mean of its divisors is an integer number (5415580176).

Almost surely, 2^21211022309 is an apocalyptic number.

It is an amenable number.

21211022309 is a deficient number, since it is larger than the sum of its proper divisors (451298395).

21211022309 is an equidigital number, since it uses as much as digits as its factorization.

21211022309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451298394.

The product of its (nonzero) digits is 432, while the sum is 23.

The spelling of 21211022309 in words is "twenty-one billion, two hundred eleven million, twenty-two thousand, three hundred nine".