18031801805 has 4 divisors (see below), whose sum is σ = 21638162172. Its totient is φ = 14425441440.

The previous prime is 18031801673. The next prime is 18031801807. The reversal of 18031801805 is 50810813081.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4370399881 + 13661401924 = 66109^2 + 116882^2 .

It is a de Polignac number, because none of the positive numbers 2^k-18031801805 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 (18031801807) 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, 1803180176 + ... + 1803180185.

It is an arithmetic number, because the mean of its divisors is an integer number (5409540543).

Almost surely, 2^18031801805 is an apocalyptic number.

It is an amenable number.

18031801805 is a deficient number, since it is larger than the sum of its proper divisors (3606360367).

18031801805 is an equidigital number, since it uses as much as digits as its factorization.

18031801805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3606360366.

The product of its (nonzero) digits is 7680, while the sum is 35.

The spelling of 18031801805 in words is "eighteen billion, thirty-one million, eight hundred one thousand, eight hundred five".