18778398894025 has 27 divisors (see below), whose sum is σ = 23520784979199. Its totient is φ = 14872245960000.

The previous prime is 18778398894011. The next prime is 18778398894029. The reversal of 18778398894025 is 52049889387781.

The square root of 18778398894025 is 4333405.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 15085867706809 + 3692531187216 = 3884053^2 + 1921596^2 .

It is not a de Polignac number, because 18778398894025 - 2⁵ = 18778398893993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18778398894029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2188365235 + ... + 2188373815.

Almost surely, 2^{18778398894025} is an apocalyptic number.

18778398894025 is the 4333405-th square number.

18778398894025 is the 2166703-rd centered octagonal number.

It is an amenable number.

18778398894025 is a deficient number, since it is larger than the sum of its proper divisors (4742386085174).

18778398894025 is an frugal number, since it uses more digits than its factorization.

18778398894025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17374 (or 8687 counting only the distinct ones).

The product of its (nonzero) digits is 1950842880, while the sum is 79.

The spelling of 18778398894025 in words is "eighteen trillion, seven hundred seventy-eight billion, three hundred ninety-eight million, eight hundred ninety-four thousand, twenty-five".