640888838 has 4 divisors (see below), whose sum is σ = 961333260. Its totient is φ = 320444418.

The previous prime is 640888819. The next prime is 640888861. The reversal of 640888838 is 838888046.

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

It is a self number, because there is not a number n which added to its sum of digits gives 640888838.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160222208 + ... + 160222211.

It is an arithmetic number, because the mean of its divisors is an integer number (240333315).

Almost surely, 2^640888838 is an apocalyptic number.

640888838 is a deficient number, since it is larger than the sum of its proper divisors (320444422).

640888838 is a wasteful number, since it uses less digits than its factorization.

640888838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320444421.

The product of its (nonzero) digits is 2359296, while the sum is 53.

The square root of 640888838 is about 25315.7823896478. The cubic root of 640888838 is about 862.1726380143.

The spelling of 640888838 in words is "six hundred forty million, eight hundred eighty-eight thousand, eight hundred thirty-eight".