640266681878 has 16 divisors (see below), whose sum is σ = 971312776560. Its totient is φ = 316504932000.

The previous prime is 640266681869. The next prime is 640266681889. The reversal of 640266681878 is 878186662046.

640266681878 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 640266681878.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2153933 + ... + 2433096.

It is an arithmetic number, because the mean of its divisors is an integer number (60707048535).

Almost surely, 2^640266681878 is an apocalyptic number.

640266681878 is a deficient number, since it is larger than the sum of its proper divisors (331046094682).

640266681878 is a wasteful number, since it uses less digits than its factorization.

640266681878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4587823.

The product of its (nonzero) digits is 37158912, while the sum is 62.

The spelling of 640266681878 in words is "six hundred forty billion, two hundred sixty-six million, six hundred eighty-one thousand, eight hundred seventy-eight".