18391884545 has 4 divisors (see below), whose sum is σ = 22070261460. Its totient is φ = 14713507632.

The previous prime is 18391884527. The next prime is 18391884547. The reversal of 18391884545 is 54548819381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54548819381 = 7 ⋅7792688483.

It can be written as a sum of positive squares in 2 ways, for example, as 7077520384 + 11314364161 = 84128^2 + 106369^2 .

It is a cyclic number.

It is not a de Polignac number, because 18391884545 - 2⁶ = 18391884481 is a prime.

It is a super-2 number, since 2×18391884545² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18391884547) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1839188450 + ... + 1839188459.

It is an arithmetic number, because the mean of its divisors is an integer number (5517565365).

Almost surely, 2^18391884545 is an apocalyptic number.

It is an amenable number.

18391884545 is a deficient number, since it is larger than the sum of its proper divisors (3678376915).

18391884545 is an equidigital number, since it uses as much as digits as its factorization.

18391884545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3678376914.

The product of its digits is 5529600, while the sum is 56.

The spelling of 18391884545 in words is "eighteen billion, three hundred ninety-one million, eight hundred eighty-four thousand, five hundred forty-five".