18000000 has 168 divisors, whose sum is σ = 64745265. Its totient is φ = 4800000.

The previous prime is 17999987. The next prime is 18000041. The reversal of 18000000 is 81.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 4 ways, for example, as 3069504 + 14930496 = 1752^2 + 3864^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3000.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 3599998 + ... + 3600002.

Almost surely, 2^18000000 is an apocalyptic number.

18000000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18000000

18000000 is an abundant number, since it is smaller than the sum of its proper divisors (46745265).

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

18000000 is an frugal number, since it uses more digits than its factorization.

18000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50 (or 10 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 18000000 is about 4242.6406871193. The cubic root of 18000000 is about 262.0741394209.

Adding to 18000000 its reverse (81), we get a palindrome (18000081).

The spelling of 18000000 in words is "eighteen million", and thus it is an aban number and an uban number.