640388418 has 16 divisors (see below), whose sum is σ = 1285151616. Its totient is φ = 212733680.

The previous prime is 640388417. The next prime is 640388449. The reversal of 640388418 is 814883046.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 640388418.

It is not an unprimeable number, because it can be changed into a prime (640388417) 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 7 ways as a sum of consecutive naturals, for example, 180378 + ... + 183893.

It is an arithmetic number, because the mean of its divisors is an integer number (80321976).

Almost surely, 2^640388418 is an apocalyptic number.

640388418 is an abundant number, since it is smaller than the sum of its proper divisors (644763198).

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

640388418 is a wasteful number, since it uses less digits than its factorization.

640388418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364569.

The product of its (nonzero) digits is 147456, while the sum is 42.

The square root of 640388418 is about 25305.8969017105. The cubic root of 640388418 is about 861.9481785087.

The spelling of 640388418 in words is "six hundred forty million, three hundred eighty-eight thousand, four hundred eighteen".