18404881 has 4 divisors (see below), whose sum is σ = 20078064. Its totient is φ = 16731700.

The previous prime is 18404843. The next prime is 18404887. The reversal of 18404881 is 18840481.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18840481 = 11 ⋅1712771.

It is a cyclic number.

It is not a de Polignac number, because 18404881 - 2⁷ = 18404753 is a prime.

It is a super-2 number, since 2×18404881² = 677479289248322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18404887) 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, 836575 + ... + 836596.

It is an arithmetic number, because the mean of its divisors is an integer number (5019516).

Almost surely, 2^18404881 is an apocalyptic number.

18404881 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18404881 is a deficient number, since it is larger than the sum of its proper divisors (1673183).

18404881 is a wasteful number, since it uses less digits than its factorization.

18404881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1673182.

The product of its (nonzero) digits is 8192, while the sum is 34.

The square root of 18404881 is about 4290.0910246754. The cubic root of 18404881 is about 264.0245663166.

Subtracting 18404881 from its reverse (18840481), we obtain a square (435600 = 660²).

The spelling of 18404881 in words is "eighteen million, four hundred four thousand, eight hundred eighty-one".