639439 has 2 divisors, whose sum is σ = 639440. Its totient is φ = 639438.

The previous prime is 639433. The next prime is 639451. The reversal of 639439 is 934936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639439 - 2⁷ = 639311 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639433) 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, 319719 + 319720.

It is an arithmetic number, because the mean of its divisors is an integer number (319720).

2⁶³⁹⁴³⁹ is an apocalyptic number.

639439 is a deficient number, since it is larger than the sum of its proper divisors (1).

639439 is an equidigital number, since it uses as much as digits as its factorization.

639439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 34.

The square root of 639439 is about 799.6492981301. The cubic root of 639439 is about 86.1522002850.

The spelling of 639439 in words is "six hundred thirty-nine thousand, four hundred thirty-nine".