640502128 has 60 divisors (see below), whose sum is σ = 1453534200. Its totient is φ = 272608896.

The previous prime is 640502087. The next prime is 640502167. The reversal of 640502128 is 821205046.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 640502096 and 640502105.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 114075 + ... + 119557.

It is an arithmetic number, because the mean of its divisors is an integer number (24225570).

Almost surely, 2^640502128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640502128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (726767100).

640502128 is an abundant number, since it is smaller than the sum of its proper divisors (813032072).

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

640502128 is a wasteful number, since it uses less digits than its factorization.

640502128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5654 (or 5641 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 640502128 is about 25308.1435115261. The cubic root of 640502128 is about 861.9991925101. Note that the first 3 decimals are identical.

The spelling of 640502128 in words is "six hundred forty million, five hundred two thousand, one hundred twenty-eight".