18518999593 has 4 divisors (see below), whose sum is σ = 18795402640. Its totient is φ = 18242596548.

The previous prime is 18518999567. The next prime is 18518999599. The reversal of 18518999593 is 39599981581.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39599981581 = 6323 ⋅6262847.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18518999593 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (67), and also a Moran number because the ratio is a prime number: 276402979 = 18518999593 / (1 + 8 + 5 + 1 + 8 + 9 + 9 + 9 + 5 + 9 + 3).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18518999599) 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, 138201423 + ... + 138201556.

It is an arithmetic number, because the mean of its divisors is an integer number (4698850660).

Almost surely, 2^18518999593 is an apocalyptic number.

It is an amenable number.

18518999593 is a deficient number, since it is larger than the sum of its proper divisors (276403047).

18518999593 is an equidigital number, since it uses as much as digits as its factorization.

18518999593 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276403046.

The product of its digits is 31492800, while the sum is 67.

The spelling of 18518999593 in words is "eighteen billion, five hundred eighteen million, nine hundred ninety-nine thousand, five hundred ninety-three".