639658289 has 4 divisors (see below), whose sum is σ = 639775524. Its totient is φ = 639541056.

The previous prime is 639658277. The next prime is 639658291. The reversal of 639658289 is 982856936.

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

It can be written as a sum of positive squares in 2 ways, for example, as 265429264 + 374229025 = 16292^2 + 19345^2 .

It is a cyclic number.

It is not a de Polignac number, because 639658289 - 2¹⁶ = 639592753 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (639658259) 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, 50012 + ... + 61485.

It is an arithmetic number, because the mean of its divisors is an integer number (159943881).

Almost surely, 2^639658289 is an apocalyptic number.

It is an amenable number.

639658289 is a deficient number, since it is larger than the sum of its proper divisors (117235).

639658289 is a wasteful number, since it uses less digits than its factorization.

639658289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117234.

The product of its digits is 5598720, while the sum is 56.

The square root of 639658289 is about 25291.4667229878. The cubic root of 639658289 is about 861.6204749513.

The spelling of 639658289 in words is "six hundred thirty-nine million, six hundred fifty-eight thousand, two hundred eighty-nine".