21808254873 has 4 divisors (see below), whose sum is σ = 29077673168. Its totient is φ = 14538836580.

The previous prime is 21808254869. The next prime is 21808254887. The reversal of 21808254873 is 37845280812.

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 21808254873 - 2² = 21808254869 is a prime.

It is a super-2 number, since 2×21808254873² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21808254803) 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, 3634709143 + ... + 3634709148.

It is an arithmetic number, because the mean of its divisors is an integer number (7269418292).

Almost surely, 2^21808254873 is an apocalyptic number.

It is an amenable number.

21808254873 is a deficient number, since it is larger than the sum of its proper divisors (7269418295).

21808254873 is an equidigital number, since it uses as much as digits as its factorization.

21808254873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7269418294.

The product of its (nonzero) digits is 860160, while the sum is 48.

The spelling of 21808254873 in words is "twenty-one billion, eight hundred eight million, two hundred fifty-four thousand, eight hundred seventy-three".