18028509 has 8 divisors (see below), whose sum is σ = 24687840. Its totient is φ = 11694096.

The previous prime is 18028499. The next prime is 18028519. The reversal of 18028509 is 90582081.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18028499) and next prime (18028519).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18028509 - 2⁵ = 18028477 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18028509.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18028519) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81099 + ... + 81320.

It is an arithmetic number, because the mean of its divisors is an integer number (3085980).

Almost surely, 2^18028509 is an apocalyptic number.

It is an amenable number.

18028509 is a deficient number, since it is larger than the sum of its proper divisors (6659331).

18028509 is a wasteful number, since it uses less digits than its factorization.

18028509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162459.

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 18028509 is about 4245.9991756947. Note that the first 3 decimals coincide. The cubic root of 18028509 is about 262.2124270243.

The spelling of 18028509 in words is "eighteen million, twenty-eight thousand, five hundred nine".