18665840 has 20 divisors (see below), whose sum is σ = 43398264. Its totient is φ = 7466304.

The previous prime is 18665837. The next prime is 18665849. The reversal of 18665840 is 4856681.

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 18665794 and 18665803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18665849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 116582 + ... + 116741.

Almost surely, 2^18665840 is an apocalyptic number.

18665840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18665840 is an abundant number, since it is smaller than the sum of its proper divisors (24732424).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18665840 is a wasteful number, since it uses less digits than its factorization.

18665840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233336 (or 233330 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 38.

The square root of 18665840 is about 4320.3981298024. The cubic root of 18665840 is about 265.2665645710.

The spelling of 18665840 in words is "eighteen million, six hundred sixty-five thousand, eight hundred forty".