18518945551 has 4 divisors (see below), whose sum is σ = 18868359672. Its totient is φ = 18169531432.

The previous prime is 18518945539. The next prime is 18518945603. The reversal of 18518945551 is 15554981581.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15554981581 = 23 ⋅676303547.

It is a cyclic number.

It is not a de Polignac number, because 18518945551 - 2³¹ = 16371461903 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 (18518945051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 174706981 + ... + 174707086.

It is an arithmetic number, because the mean of its divisors is an integer number (4717089918).

Almost surely, 2^18518945551 is an apocalyptic number.

18518945551 is a deficient number, since it is larger than the sum of its proper divisors (349414121).

18518945551 is an equidigital number, since it uses as much as digits as its factorization.

18518945551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349414120.

The product of its digits is 1440000, while the sum is 52.

The spelling of 18518945551 in words is "eighteen billion, five hundred eighteen million, nine hundred forty-five thousand, five hundred fifty-one".