640582709 has 8 divisors (see below), whose sum is σ = 690943512. Its totient is φ = 590376960.

The previous prime is 640582699. The next prime is 640582717. The reversal of 640582709 is 907285046.

It can be written as a sum of positive squares in 4 ways, for example, as 317374225 + 323208484 = 17815^2 + 17978^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640582709 - 2¹⁶ = 640517173 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640582799) 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 7 ways as a sum of consecutive naturals, for example, 30104 + ... + 46769.

It is an arithmetic number, because the mean of its divisors is an integer number (86367939).

Almost surely, 2^640582709 is an apocalyptic number.

It is an amenable number.

640582709 is a deficient number, since it is larger than the sum of its proper divisors (50360803).

640582709 is a wasteful number, since it uses less digits than its factorization.

640582709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77527.

The product of its (nonzero) digits is 120960, while the sum is 41.

The square root of 640582709 is about 25309.7354589099. The cubic root of 640582709 is about 862.0353401101.

The spelling of 640582709 in words is "six hundred forty million, five hundred eighty-two thousand, seven hundred nine".