640299609 has 6 divisors (see below), whose sum is σ = 924877226. Its totient is φ = 426866400.

The previous prime is 640299607. The next prime is 640299617. The reversal of 640299609 is 906992046.

It can be written as a sum of positive squares in only one way, i.e., 638673984 + 1625625 = 25272^2 + 1275^2 .

It is not a de Polignac number, because 640299609 - 2¹ = 640299607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640299607) 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 5 ways as a sum of consecutive naturals, for example, 35572192 + ... + 35572209.

Almost surely, 2^640299609 is an apocalyptic number.

It is an amenable number.

640299609 is a deficient number, since it is larger than the sum of its proper divisors (284577617).

640299609 is a wasteful number, since it uses less digits than its factorization.

640299609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71144407 (or 71144404 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 45.

The square root of 640299609 is about 25304.1421312796. The cubic root of 640299609 is about 861.9083317051.

The spelling of 640299609 in words is "six hundred forty million, two hundred ninety-nine thousand, six hundred nine".