640240128 has 240 divisors, whose sum is σ = 2137202496. Its totient is φ = 182353920.

The previous prime is 640240123. The next prime is 640240129. The reversal of 640240128 is 821042046.

640240128 is a `hidden beast` number, since 640 + 2 + 4 + 0 + 12 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (640240123) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 861325 + ... + 862067.

Almost surely, 2^640240128 is an apocalyptic number.

640240128 is a gapful number since it is divisible by the number (68) 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 640240128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1068601248).

640240128 is an abundant number, since it is smaller than the sum of its proper divisors (1496962368).

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

640240128 is a wasteful number, since it uses less digits than its factorization.

640240128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 795 (or 776 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 640240128 is about 25302.9667825731. The cubic root of 640240128 is about 861.8816417221.

The spelling of 640240128 in words is "six hundred forty million, two hundred forty thousand, one hundred twenty-eight".