18209840 has 40 divisors (see below), whose sum is σ = 46189008. Its totient is φ = 6621440.

The previous prime is 18209833. The next prime is 18209843. The reversal of 18209840 is 4890281.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 18209797 and 18209806.

It is not an unprimeable number, because it can be changed into a prime (18209843) 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 7 ways as a sum of consecutive naturals, for example, 9467 + ... + 11226.

Almost surely, 2^18209840 is an apocalyptic number.

18209840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18209840 is an abundant number, since it is smaller than the sum of its proper divisors (27979168).

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

18209840 is a wasteful number, since it uses less digits than its factorization.

18209840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20717 (or 20711 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 18209840 is about 4267.2989114896. The cubic root of 18209840 is about 263.0886081171.

The spelling of 18209840 in words is "eighteen million, two hundred nine thousand, eight hundred forty".