18000444 has 144 divisors (see below), whose sum is σ = 56077056. Its totient is φ = 4472160.

The previous prime is 18000439. The next prime is 18000457. The reversal of 18000444 is 44400081.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 18000444.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 782617 + ... + 782639.

It is an arithmetic number, because the mean of its divisors is an integer number (389424).

Almost surely, 2^18000444 is an apocalyptic number.

18000444 is a gapful number since it is divisible by the number (14) 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 18000444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28038528).

18000444 is an abundant number, since it is smaller than the sum of its proper divisors (38076612).

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

18000444 is a wasteful number, since it uses less digits than its factorization.

18000444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 18000444 is about 4242.6930126984. The cubic root of 18000444 is about 262.0762942350.

The spelling of 18000444 in words is "eighteen million, four hundred forty-four", and thus it is an aban number.