640385539 has 4 divisors (see below), whose sum is σ = 645060024. Its totient is φ = 635711056.

The previous prime is 640385533. The next prime is 640385579. The reversal of 640385539 is 935583046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640385539 - 2⁷ = 640385411 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640385495 and 640385504.

It is not an unprimeable number, because it can be changed into a prime (640385533) 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 in 3 ways as a sum of consecutive naturals, for example, 2337037 + ... + 2337310.

It is an arithmetic number, because the mean of its divisors is an integer number (161265006).

Almost surely, 2^640385539 is an apocalyptic number.

640385539 is a deficient number, since it is larger than the sum of its proper divisors (4674485).

640385539 is a wasteful number, since it uses less digits than its factorization.

640385539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4674484.

The product of its (nonzero) digits is 388800, while the sum is 43.

The square root of 640385539 is about 25305.8400176718. The cubic root of 640385539 is about 861.9468868174.

The spelling of 640385539 in words is "six hundred forty million, three hundred eighty-five thousand, five hundred thirty-nine".