18438840 has 192 divisors, whose sum is σ = 71285760. Its totient is φ = 4199040.

The previous prime is 18438821. The next prime is 18438841. The reversal of 18438840 is 4883481.

18438840 = T₂₂₅ + T₂₂₆ + ... + T₄₉₅.

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 = 18438795 and 18438804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18438841) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 67905 + ... + 68175.

It is an arithmetic number, because the mean of its divisors is an integer number (371280).

Almost surely, 2^18438840 is an apocalyptic number.

18438840 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 18438840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35642880).

18438840 is an abundant number, since it is smaller than the sum of its proper divisors (52846920).

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

18438840 is a wasteful number, since it uses less digits than its factorization.

18438840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304 (or 288 counting only the distinct ones).

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

The square root of 18438840 is about 4294.0470421270. The cubic root of 18438840 is about 264.1868511923.

The spelling of 18438840 in words is "eighteen million, four hundred thirty-eight thousand, eight hundred forty".