640887198 has 32 divisors (see below), whose sum is σ = 1465724160. Its totient is φ = 183005760.

The previous prime is 640887173. The next prime is 640887217. The reversal of 640887198 is 891788046.

640887198 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 640887198.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 98098 + ... + 104426.

It is an arithmetic number, because the mean of its divisors is an integer number (45803880).

Almost surely, 2^640887198 is an apocalyptic number.

640887198 is an abundant number, since it is smaller than the sum of its proper divisors (824836962).

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

640887198 is a wasteful number, since it uses less digits than its factorization.

640887198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8752.

The product of its (nonzero) digits is 774144, while the sum is 51.

The square root of 640887198 is about 25315.7499987656. The cubic root of 640887198 is about 862.1719025959.

The spelling of 640887198 in words is "six hundred forty million, eight hundred eighty-seven thousand, one hundred ninety-eight".