640289238 has 8 divisors (see below), whose sum is σ = 1280578488. Its totient is φ = 213429744.

The previous prime is 640289219. The next prime is 640289239. The reversal of 640289238 is 832982046.

It is a sphenic number, since it is the product of 3 distinct primes.

640289238 is an admirable number.

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 Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 640289238.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640289239) 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, 53357431 + ... + 53357442.

It is an arithmetic number, because the mean of its divisors is an integer number (160072311).

Almost surely, 2^640289238 is an apocalyptic number.

640289238 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

640289238 is a wasteful number, since it uses less digits than its factorization.

640289238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106714878.

The product of its (nonzero) digits is 165888, while the sum is 42.

The square root of 640289238 is about 25303.9372035263. The cubic root of 640289238 is about 861.9036782067.

The spelling of 640289238 in words is "six hundred forty million, two hundred eighty-nine thousand, two hundred thirty-eight".