18040085821 has 4 divisors (see below), whose sum is σ = 18042112444. Its totient is φ = 18038059200.

The previous prime is 18040085783. The next prime is 18040085873. The reversal of 18040085821 is 12858004081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12858004081 = 13 ⋅989077237.

It can be written as a sum of positive squares in 2 ways, for example, as 14784128100 + 3255957721 = 121590^2 + 57061^2 .

It is a cyclic number.

It is not a de Polignac number, because 18040085821 - 2¹¹ = 18040083773 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 (18040085881) 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, 999900 + ... + 1017781.

It is an arithmetic number, because the mean of its divisors is an integer number (4510528111).

Almost surely, 2^18040085821 is an apocalyptic number.

It is an amenable number.

18040085821 is a deficient number, since it is larger than the sum of its proper divisors (2026623).

18040085821 is an equidigital number, since it uses as much as digits as its factorization.

18040085821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2026622.

The product of its (nonzero) digits is 20480, while the sum is 37.

The spelling of 18040085821 in words is "eighteen billion, forty million, eighty-five thousand, eight hundred twenty-one".