640246864 has 10 divisors (see below), whose sum is σ = 1240478330. Its totient is φ = 320123424.

The previous prime is 640246861. The next prime is 640246897. The reversal of 640246864 is 468642046.

It can be written as a sum of positive squares in only one way, i.e., 614643264 + 25603600 = 24792^2 + 5060^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640246861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20007699 + ... + 20007730.

It is an arithmetic number, because the mean of its divisors is an integer number (124047833).

Almost surely, 2^640246864 is an apocalyptic number.

It is an amenable number.

640246864 is a deficient number, since it is larger than the sum of its proper divisors (600231466).

640246864 is a wasteful number, since it uses less digits than its factorization.

640246864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40015437 (or 40015431 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 40.

The square root of 640246864 is about 25303.0998891440. The cubic root of 640246864 is about 861.8846643455.

The spelling of 640246864 in words is "six hundred forty million, two hundred forty-six thousand, eight hundred sixty-four".