6439639 has 2 divisors, whose sum is σ = 6439640. Its totient is φ = 6439638.

The previous prime is 6439619. The next prime is 6439679. The reversal of 6439639 is 9369346.

It is an a-pointer prime, because the next prime (6439679) can be obtained adding 6439639 to its sum of digits (40).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6439639 - 2⁵ = 6439607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6439619) 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, 3219819 + 3219820.

It is an arithmetic number, because the mean of its divisors is an integer number (3219820).

Almost surely, 2^6439639 is an apocalyptic number.

6439639 is a deficient number, since it is larger than the sum of its proper divisors (1).

6439639 is an equidigital number, since it uses as much as digits as its factorization.

6439639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 104976, while the sum is 40.

The square root of 6439639 is about 2537.6443801289. The cubic root of 6439639 is about 186.0460729124.

The spelling of 6439639 in words is "six million, four hundred thirty-nine thousand, six hundred thirty-nine".