128663640 has 384 divisors, whose sum is σ = 519966720. Its totient is φ = 27993600.

The previous prime is 128663621. The next prime is 128663653. The reversal of 128663640 is 46366821.

128663640 is a `hidden beast` number, since 1 + 2 + 8 + 6 + 6 + 3 + 640 = 666.

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 = 128663595 and 128663604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2109210 + ... + 2109270.

It is an arithmetic number, because the mean of its divisors is an integer number (1354080).

Almost surely, 2^128663640 is an apocalyptic number.

128663640 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 128663640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (259983360).

128663640 is an abundant number, since it is smaller than the sum of its proper divisors (391303080).

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

128663640 is a wasteful number, since it uses less digits than its factorization.

128663640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 109 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 128663640 is about 11342.9996032795. Note that the first 3 decimals coincide. The cubic root of 128663640 is about 504.8378919603.

The spelling of 128663640 in words is "one hundred twenty-eight million, six hundred sixty-three thousand, six hundred forty".