640776213864 has 24 divisors (see below), whose sum is σ = 1735435579410. Its totient is φ = 213592071264.

The previous prime is 640776213859. The next prime is 640776213899. The reversal of 640776213864 is 468312677046.

640776213864 is a `hidden beast` number, since 6 + 4 + 0 + 7 + 7 + 621 + 3 + 8 + 6 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 398375568900 + 242400644964 = 631170^2 + 492342^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a self number, because there is not a number n which added to its sum of digits gives 640776213864.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4449834747 + ... + 4449834890.

Almost surely, 2^640776213864 is an apocalyptic number.

It is an amenable number.

640776213864 is an abundant number, since it is smaller than the sum of its proper divisors (1094659365546).

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

640776213864 is a wasteful number, since it uses less digits than its factorization.

640776213864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8899669649 (or 8899669642 counting only the distinct ones).

The product of its (nonzero) digits is 8128512, while the sum is 54.

The spelling of 640776213864 in words is "six hundred forty billion, seven hundred seventy-six million, two hundred thirteen thousand, eight hundred sixty-four".