21803710765 has 4 divisors (see below), whose sum is σ = 26164452924. Its totient is φ = 17442968608.

The previous prime is 21803710727. The next prime is 21803710771. The reversal of 21803710765 is 56701730812.

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 5771592841 + 16032117924 = 75971^2 + 126618^2 .

It is a cyclic number.

It is not a de Polignac number, because 21803710765 - 2²⁵ = 21770156333 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 2180371072 + ... + 2180371081.

It is an arithmetic number, because the mean of its divisors is an integer number (6541113231).

Almost surely, 2^21803710765 is an apocalyptic number.

It is an amenable number.

21803710765 is a deficient number, since it is larger than the sum of its proper divisors (4360742159).

21803710765 is an equidigital number, since it uses as much as digits as its factorization.

21803710765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4360742158.

The product of its (nonzero) digits is 70560, while the sum is 40.

The spelling of 21803710765 in words is "twenty-one billion, eight hundred three million, seven hundred ten thousand, seven hundred sixty-five".