18039840 has 288 divisors, whose sum is σ = 72394560. Its totient is φ = 3741696.

The previous prime is 18039823. The next prime is 18039871. The reversal of 18039840 is 4893081.

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 305731 + ... + 305789.

It is an arithmetic number, because the mean of its divisors is an integer number (251370).

Almost surely, 2^18039840 is an apocalyptic number.

18039840 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 18039840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36197280).

18039840 is an abundant number, since it is smaller than the sum of its proper divisors (54354720).

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

18039840 is a wasteful number, since it uses less digits than its factorization.

18039840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 18039840 is about 4247.3332810129. Note that the first 3 decimals coincide. The cubic root of 18039840 is about 262.2673494211.

The spelling of 18039840 in words is "eighteen million, thirty-nine thousand, eight hundred forty".