128409840 has 320 divisors, whose sum is σ = 506217600. Its totient is φ = 29638656.

The previous prime is 128409821. The next prime is 128409889. The reversal of 128409840 is 48904821.

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 = 128409795 and 128409804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 477226 + ... + 477494.

It is an arithmetic number, because the mean of its divisors is an integer number (1581930).

Almost surely, 2^128409840 is an apocalyptic number.

128409840 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 128409840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (253108800).

128409840 is an abundant number, since it is smaller than the sum of its proper divisors (377807760).

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

128409840 is a wasteful number, since it uses less digits than its factorization.

128409840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 128409840 is about 11331.8065638273. The cubic root of 128409840 is about 504.5057281956.

The spelling of 128409840 in words is "one hundred twenty-eight million, four hundred nine thousand, eight hundred forty".