640811870 has 16 divisors (see below), whose sum is σ = 1175225760. Its totient is φ = 251488224.

The previous prime is 640811851. The next prime is 640811911. The reversal of 640811870 is 78118046.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 640811870.

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 7 ways as a sum of consecutive naturals, for example, 604010 + ... + 605069.

It is an arithmetic number, because the mean of its divisors is an integer number (73451610).

Almost surely, 2^640811870 is an apocalyptic number.

640811870 is a deficient number, since it is larger than the sum of its proper divisors (534413890).

640811870 is a wasteful number, since it uses less digits than its factorization.

640811870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1209139.

The product of its (nonzero) digits is 10752, while the sum is 35.

The square root of 640811870 is about 25314.2621855744. The cubic root of 640811870 is about 862.1381222208.

The spelling of 640811870 in words is "six hundred forty million, eight hundred eleven thousand, eight hundred seventy".