18009840 has 40 divisors (see below), whose sum is σ = 55831248. Its totient is φ = 4802560.

The previous prime is 18009833. The next prime is 18009857. The reversal of 18009840 is 4890081.

It is a happy number.

18009840 is nontrivially palindromic in base 9.

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

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 18009798 and 18009807.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37281 + ... + 37760.

Almost surely, 2^18009840 is an apocalyptic number.

18009840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18009840 is an abundant number, since it is smaller than the sum of its proper divisors (37821408).

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

18009840 is a wasteful number, since it uses less digits than its factorization.

18009840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75057 (or 75051 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 18009840 is about 4243.8001837975. The cubic root of 18009840 is about 262.1218864534.

The spelling of 18009840 in words is "eighteen million, nine thousand, eight hundred forty".