18363978761 has 4 divisors (see below), whose sum is σ = 18811880724. Its totient is φ = 17916076800.

The previous prime is 18363978707. The next prime is 18363978779. The reversal of 18363978761 is 16787936381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16787936381 = 19 ⋅883575599.

It can be written as a sum of positive squares in 2 ways, for example, as 776179600 + 17587799161 = 27860^2 + 132619^2 .

It is a cyclic number.

It is not a de Polignac number, because 18363978761 - 2²⁶ = 18296869897 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 18363978761.

It is not an unprimeable number, because it can be changed into a prime (18363978361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 223950920 + ... + 223951001.

It is an arithmetic number, because the mean of its divisors is an integer number (4702970181).

Almost surely, 2^18363978761 is an apocalyptic number.

It is an amenable number.

18363978761 is a deficient number, since it is larger than the sum of its proper divisors (447901963).

18363978761 is an equidigital number, since it uses as much as digits as its factorization.

18363978761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447901962.

The product of its digits is 9144576, while the sum is 59.

The spelling of 18363978761 in words is "eighteen billion, three hundred sixty-three million, nine hundred seventy-eight thousand, seven hundred sixty-one".