640862866 has 24 divisors (see below), whose sum is σ = 1148469516. Its totient is φ = 267230880.

The previous prime is 640862861. The next prime is 640862879. The reversal of 640862866 is 668268046.

It can be written as a sum of positive squares in 2 ways, for example, as 640343025 + 519841 = 25305^2 + 721^2 .

It is not an unprimeable number, because it can be changed into a prime (640862861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 84745 + ... + 91996.

Almost surely, 2^640862866 is an apocalyptic number.

640862866 is a deficient number, since it is larger than the sum of its proper divisors (507606650).

640862866 is a wasteful number, since it uses less digits than its factorization.

640862866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176794 (or 176787 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 46.

The square root of 640862866 is about 25315.2694238082. The cubic root of 640862866 is about 862.1609913506.

The spelling of 640862866 in words is "six hundred forty million, eight hundred sixty-two thousand, eight hundred sixty-six".