640028859 has 4 divisors (see below), whose sum is σ = 853371816. Its totient is φ = 426685904.

The previous prime is 640028833. The next prime is 640028863. The reversal of 640028859 is 958820046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640028859 - 2⁵ = 640028827 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640028859.

It is not an unprimeable number, because it can be changed into a prime (640728859) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 106671474 + ... + 106671479.

It is an arithmetic number, because the mean of its divisors is an integer number (213342954).

Almost surely, 2^640028859 is an apocalyptic number.

640028859 is a deficient number, since it is larger than the sum of its proper divisors (213342957).

640028859 is a wasteful number, since it uses less digits than its factorization.

640028859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213342956.

The product of its (nonzero) digits is 138240, while the sum is 42.

The square root of 640028859 is about 25298.7916509860. The cubic root of 640028859 is about 861.7868289078.

The spelling of 640028859 in words is "six hundred forty million, twenty-eight thousand, eight hundred fifty-nine".