18388440 has 96 divisors (see below), whose sum is σ = 68309280. Its totient is φ = 4202496.

The previous prime is 18388429. The next prime is 18388453. The reversal of 18388440 is 4488381.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 18388395 and 18388404.

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 23 ways as a sum of consecutive naturals, for example, 1129 + ... + 6168.

It is an arithmetic number, because the mean of its divisors is an integer number (711555).

Almost surely, 2^18388440 is an apocalyptic number.

18388440 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 18388440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34154640).

18388440 is an abundant number, since it is smaller than the sum of its proper divisors (49920840).

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

18388440 is a wasteful number, since it uses less digits than its factorization.

18388440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7321 (or 7314 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The square root of 18388440 is about 4288.1744367504. The cubic root of 18388440 is about 263.9459255639.

The spelling of 18388440 in words is "eighteen million, three hundred eighty-eight thousand, four hundred forty".