640738878893 has 4 divisors (see below), whose sum is σ = 640740554688. Its totient is φ = 640737203100.

The previous prime is 640738878859. The next prime is 640738878911. The reversal of 640738878893 is 398878837046.

640738878893 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640738878893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640738878833) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47468 + ... + 1133018.

It is an arithmetic number, because the mean of its divisors is an integer number (160185138672).

Almost surely, 2^640738878893 is an apocalyptic number.

It is an amenable number.

640738878893 is a deficient number, since it is larger than the sum of its proper divisors (1675795).

640738878893 is a wasteful number, since it uses less digits than its factorization.

640738878893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1675794.

The product of its (nonzero) digits is 390168576, while the sum is 71.

The spelling of 640738878893 in words is "six hundred forty billion, seven hundred thirty-eight million, eight hundred seventy-eight thousand, eight hundred ninety-three".