6639439 has 2 divisors, whose sum is σ = 6639440. Its totient is φ = 6639438.

The previous prime is 6639407. The next prime is 6639449. The reversal of 6639439 is 9349366.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6639439 - 2⁵ = 6639407 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6639449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3319719 + 3319720.

It is an arithmetic number, because the mean of its divisors is an integer number (3319720).

Almost surely, 2^6639439 is an apocalyptic number.

6639439 is a deficient number, since it is larger than the sum of its proper divisors (1).

6639439 is an equidigital number, since it uses as much as digits as its factorization.

6639439 is an evil number, because the sum of its binary digits is even.

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

The square root of 6639439 is about 2576.7108879345. The cubic root of 6639439 is about 187.9506340129.

The spelling of 6639439 in words is "six million, six hundred thirty-nine thousand, four hundred thirty-nine".