18404066891 has 4 divisors (see below), whose sum is σ = 21033219312. Its totient is φ = 15774914472.

The previous prime is 18404066833. The next prime is 18404066897. The reversal of 18404066891 is 19866040481.

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 18404066891 - 2³⁴ = 1224197707 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18404066897) 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, 1314576200 + ... + 1314576213.

It is an arithmetic number, because the mean of its divisors is an integer number (5258304828).

Almost surely, 2^18404066891 is an apocalyptic number.

18404066891 is a deficient number, since it is larger than the sum of its proper divisors (2629152421).

18404066891 is an equidigital number, since it uses as much as digits as its factorization.

18404066891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2629152420.

The product of its (nonzero) digits is 331776, while the sum is 47.

The spelling of 18404066891 in words is "eighteen billion, four hundred four million, sixty-six thousand, eight hundred ninety-one".