6439985 has 4 divisors (see below), whose sum is σ = 7727988. Its totient is φ = 5151984.

The previous prime is 6439969. The next prime is 6439997. The reversal of 6439985 is 5899346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4700224 + 1739761 = 2168^2 + 1319^2 .

It is a cyclic number.

It is not a de Polignac number, because 6439985 - 2⁴ = 6439969 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 643994 + ... + 644003.

It is an arithmetic number, because the mean of its divisors is an integer number (1931997).

Almost surely, 2^6439985 is an apocalyptic number.

It is an amenable number.

6439985 is a deficient number, since it is larger than the sum of its proper divisors (1288003).

6439985 is a wasteful number, since it uses less digits than its factorization.

6439985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288002.

The product of its digits is 233280, while the sum is 44.

The square root of 6439985 is about 2537.7125526742. The cubic root of 6439985 is about 186.0494049205.

The spelling of 6439985 in words is "six million, four hundred thirty-nine thousand, nine hundred eighty-five".