1815109638785 has 4 divisors (see below), whose sum is σ = 2178131566548. Its totient is φ = 1452087711024.

The previous prime is 1815109638779. The next prime is 1815109638821. The reversal of 1815109638785 is 5878369015181.

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 1013612009089 + 801497629696 = 1006783^2 + 895264^2 .

It is a cyclic number.

It is not a de Polignac number, because 1815109638785 - 2²⁰ = 1815108590209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 181510963874 + ... + 181510963883.

It is an arithmetic number, because the mean of its divisors is an integer number (544532891637).

Almost surely, 2^{1815109638785} is an apocalyptic number.

It is an amenable number.

1815109638785 is a deficient number, since it is larger than the sum of its proper divisors (363021927763).

1815109638785 is an equidigital number, since it uses as much as digits as its factorization.

1815109638785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363021927762.

The product of its (nonzero) digits is 14515200, while the sum is 62.

The spelling of 1815109638785 in words is "one trillion, eight hundred fifteen billion, one hundred nine million, six hundred thirty-eight thousand, seven hundred eighty-five".