1808328727861 has 4 divisors (see below), whose sum is σ = 1808337862924. Its totient is φ = 1808319592800.

The previous prime is 1808328727859. The next prime is 1808328727903. The reversal of 1808328727861 is 1687278238081.

It is a happy number.

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 1132694046961 + 675634680900 = 1064281^2 + 821970^2 .

It is a cyclic number.

It is not a de Polignac number, because 1808328727861 - 2¹ = 1808328727859 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1808328727861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1808328727811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4263870 + ... + 4668751.

It is an arithmetic number, because the mean of its divisors is an integer number (452084465731).

Almost surely, 2^{1808328727861} is an apocalyptic number.

It is an amenable number.

1808328727861 is a deficient number, since it is larger than the sum of its proper divisors (9135063).

1808328727861 is an equidigital number, since it uses as much as digits as its factorization.

1808328727861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9135062.

The product of its (nonzero) digits is 14450688, while the sum is 61.

The spelling of 1808328727861 in words is "one trillion, eight hundred eight billion, three hundred twenty-eight million, seven hundred twenty-seven thousand, eight hundred sixty-one".