18185428991 has 4 divisors (see below), whose sum is σ = 18307479000. Its totient is φ = 18063378984.

The previous prime is 18185428973. The next prime is 18185429077. The reversal of 18185428991 is 19982458181.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18185428991 - 2¹⁴ = 18185412607 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 (18185428901) 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, 61024781 + ... + 61025078.

It is an arithmetic number, because the mean of its divisors is an integer number (4576869750).

Almost surely, 2^18185428991 is an apocalyptic number.

18185428991 is a deficient number, since it is larger than the sum of its proper divisors (122050009).

18185428991 is a wasteful number, since it uses less digits than its factorization.

18185428991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122050008.

The product of its digits is 1658880, while the sum is 56.

The spelling of 18185428991 in words is "eighteen billion, one hundred eighty-five million, four hundred twenty-eight thousand, nine hundred ninety-one".