21773161765 has 4 divisors (see below), whose sum is σ = 26127794124. Its totient is φ = 17418529408.

The previous prime is 21773161733. The next prime is 21773161771. The reversal of 21773161765 is 56716137712.

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 6358946049 + 15414215716 = 79743^2 + 124154^2 .

It is a cyclic number.

It is not a de Polignac number, because 21773161765 - 2⁵ = 21773161733 is a prime.

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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2177316172 + ... + 2177316181.

It is an arithmetic number, because the mean of its divisors is an integer number (6531948531).

Almost surely, 2^21773161765 is an apocalyptic number.

It is an amenable number.

21773161765 is a deficient number, since it is larger than the sum of its proper divisors (4354632359).

21773161765 is an equidigital number, since it uses as much as digits as its factorization.

21773161765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4354632358.

The product of its digits is 370440, while the sum is 46.

The spelling of 21773161765 in words is "twenty-one billion, seven hundred seventy-three million, one hundred sixty-one thousand, seven hundred sixty-five".