6439729 has 2 divisors, whose sum is σ = 6439730. Its totient is φ = 6439728.

The previous prime is 6439717. The next prime is 6439751. The reversal of 6439729 is 9279346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6051600 + 388129 = 2460^2 + 623^2 .

It is a cyclic number.

It is not a de Polignac number, because 6439729 - 2⁹ = 6439217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6439691 and 6439700.

It is not a weakly prime, because it can be changed into another prime (6439759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3219864 + 3219865.

It is an arithmetic number, because the mean of its divisors is an integer number (3219865).

Almost surely, 2^6439729 is an apocalyptic number.

It is an amenable number.

6439729 is a deficient number, since it is larger than the sum of its proper divisors (1).

6439729 is an equidigital number, since it uses as much as digits as its factorization.

6439729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 40.

The square root of 6439729 is about 2537.6621130481. The cubic root of 6439729 is about 186.0469396312.

It can be divided in two parts, 64 and 39729, that added together give a palindrome (39793).

The spelling of 6439729 in words is "six million, four hundred thirty-nine thousand, seven hundred twenty-nine".