18236978413 has 4 divisors (see below), whose sum is σ = 18237919228. Its totient is φ = 18236037600.

The previous prime is 18236978401. The next prime is 18236978423. The reversal of 18236978413 is 31487963281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31487963281 = 31 ⋅1015740751.

It can be written as a sum of positive squares in 2 ways, for example, as 8128284649 + 10108693764 = 90157^2 + 100542^2 .

It is a cyclic number.

It is not a de Polignac number, because 18236978413 - 2⁵ = 18236978381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18236978423) 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, 440706 + ... + 480307.

It is an arithmetic number, because the mean of its divisors is an integer number (4559479807).

Almost surely, 2^18236978413 is an apocalyptic number.

It is an amenable number.

18236978413 is a deficient number, since it is larger than the sum of its proper divisors (940815).

18236978413 is an equidigital number, since it uses as much as digits as its factorization.

18236978413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 940814.

The product of its digits is 1741824, while the sum is 52.

The spelling of 18236978413 in words is "eighteen billion, two hundred thirty-six million, nine hundred seventy-eight thousand, four hundred thirteen".