640000387855 has 4 divisors (see below), whose sum is σ = 768000465432. Its totient is φ = 512000310280.

The previous prime is 640000387751. The next prime is 640000387909. The reversal of 640000387855 is 558783000046.

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

It is not a de Polignac number, because 640000387855 - 2¹¹ = 640000385807 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64000038781 + ... + 64000038790.

It is an arithmetic number, because the mean of its divisors is an integer number (192000116358).

Almost surely, 2^640000387855 is an apocalyptic number.

640000387855 is a deficient number, since it is larger than the sum of its proper divisors (128000077577).

640000387855 is a wasteful number, since it uses less digits than its factorization.

640000387855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128000077576.

The product of its (nonzero) digits is 806400, while the sum is 46.

The spelling of 640000387855 in words is "six hundred forty billion, three hundred eighty-seven thousand, eight hundred fifty-five".