21808884309 has 4 divisors (see below), whose sum is σ = 29078512416. Its totient is φ = 14539256204.

The previous prime is 21808884289. The next prime is 21808884311. The reversal of 21808884309 is 90348880812.

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-21808884309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808885309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3634814049 + ... + 3634814054.

It is an arithmetic number, because the mean of its divisors is an integer number (7269628104).

Almost surely, 2^21808884309 is an apocalyptic number.

It is an amenable number.

21808884309 is a deficient number, since it is larger than the sum of its proper divisors (7269628107).

21808884309 is an equidigital number, since it uses as much as digits as its factorization.

21808884309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7269628106.

The product of its (nonzero) digits is 884736, while the sum is 51.

The spelling of 21808884309 in words is "twenty-one billion, eight hundred eight million, eight hundred eighty-four thousand, three hundred nine".