18365811557 has 4 divisors (see below), whose sum is σ = 18375650496. Its totient is φ = 18355972620.

The previous prime is 18365811551. The next prime is 18365811577. The reversal of 18365811557 is 75511856381.

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.

It is a cyclic number.

It is not a de Polignac number, because 18365811557 - 2⁶ = 18365811493 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 (18365811551) 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, 4916669 + ... + 4920402.

It is an arithmetic number, because the mean of its divisors is an integer number (4593912624).

Almost surely, 2^18365811557 is an apocalyptic number.

It is an amenable number.

18365811557 is a deficient number, since it is larger than the sum of its proper divisors (9838939).

18365811557 is an equidigital number, since it uses as much as digits as its factorization.

18365811557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9838938.

The product of its digits is 1008000, while the sum is 50.

The spelling of 18365811557 in words is "eighteen billion, three hundred sixty-five million, eight hundred eleven thousand, five hundred fifty-seven".