18042881 has 4 divisors (see below), whose sum is σ = 18245700. Its totient is φ = 17840064.

The previous prime is 18042859. The next prime is 18042887. The reversal of 18042881 is 18824081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18824081 = 2617 ⋅7193.

It can be written as a sum of positive squares in 2 ways, for example, as 11282881 + 6760000 = 3359^2 + 2600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18042881 is a prime.

It is a super-2 number, since 2×18042881² = 651091109560322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18042887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101276 + ... + 101453.

It is an arithmetic number, because the mean of its divisors is an integer number (4561425).

Almost surely, 2^18042881 is an apocalyptic number.

It is an amenable number.

18042881 is a deficient number, since it is larger than the sum of its proper divisors (202819).

18042881 is an equidigital number, since it uses as much as digits as its factorization.

18042881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202818.

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 18042881 is about 4247.6912552586. The cubic root of 18042881 is about 262.2820855126.

The spelling of 18042881 in words is "eighteen million, forty-two thousand, eight hundred eighty-one".