1821678564773 has 4 divisors (see below), whose sum is σ = 1822432261260. Its totient is φ = 1820924868288.

The previous prime is 1821678564767. The next prime is 1821678564799. The reversal of 1821678564773 is 3774658761281.

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 1779857496769 + 41821068004 = 1334113^2 + 204502^2 .

It is a cyclic number.

It is not a de Polignac number, because 1821678564773 - 2²⁸ = 1821410129317 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 (1821678564763) 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, 376844618 + ... + 376849451.

It is an arithmetic number, because the mean of its divisors is an integer number (455608065315).

Almost surely, 2^{1821678564773} is an apocalyptic number.

It is an amenable number.

1821678564773 is a deficient number, since it is larger than the sum of its proper divisors (753696487).

1821678564773 is an equidigital number, since it uses as much as digits as its factorization.

1821678564773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 753696486.

The product of its digits is 94832640, while the sum is 65.

The spelling of 1821678564773 in words is "one trillion, eight hundred twenty-one billion, six hundred seventy-eight million, five hundred sixty-four thousand, seven hundred seventy-three".