6439649 has 4 divisors (see below), whose sum is σ = 6464964. Its totient is φ = 6414336.

The previous prime is 6439639. The next prime is 6439679. The reversal of 6439649 is 9469346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9469346 = 2 ⋅4734673.

It can be written as a sum of positive squares in 2 ways, for example, as 4389025 + 2050624 = 2095^2 + 1432^2 .

It is a cyclic number.

It is not a de Polignac number, because 6439649 - 2²⁰ = 5391073 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6439619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12272 + ... + 12785.

It is an arithmetic number, because the mean of its divisors is an integer number (1616241).

Almost surely, 2^6439649 is an apocalyptic number.

It is an amenable number.

6439649 is a deficient number, since it is larger than the sum of its proper divisors (25315).

6439649 is a wasteful number, since it uses less digits than its factorization.

6439649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25314.

The product of its digits is 139968, while the sum is 41.

The square root of 6439649 is about 2537.6463504594. The cubic root of 6439649 is about 186.0461692148.

The spelling of 6439649 in words is "six million, four hundred thirty-nine thousand, six hundred forty-nine".