640515864438 has 16 divisors (see below), whose sum is σ = 1423368587760. Its totient is φ = 213505288128.

The previous prime is 640515864433. The next prime is 640515864479. The reversal of 640515864438 is 834468515046.

640515864438 is a `hidden beast` number, since 6 + 4 + 0 + 51 + 586 + 4 + 4 + 3 + 8 = 666.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54), and also a Moran number because the ratio is a prime number: 11861404897 = 640515864438 / (6 + 4 + 0 + 5 + 1 + 5 + 8 + 6 + 4 + 4 + 3 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640515864433) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5930702395 + ... + 5930702502.

It is an arithmetic number, because the mean of its divisors is an integer number (88960536735).

Almost surely, 2^640515864438 is an apocalyptic number.

640515864438 is an abundant number, since it is smaller than the sum of its proper divisors (782852723322).

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

640515864438 is a wasteful number, since it uses less digits than its factorization.

640515864438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11861404908 (or 11861404902 counting only the distinct ones).

The product of its (nonzero) digits is 11059200, while the sum is 54.

The spelling of 640515864438 in words is "six hundred forty billion, five hundred fifteen million, eight hundred sixty-four thousand, four hundred thirty-eight".