6640385 has 4 divisors (see below), whose sum is σ = 7968468. Its totient is φ = 5312304.

The previous prime is 6640373. The next prime is 6640393. The reversal of 6640385 is 5830466.

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 913936 + 5726449 = 956^2 + 2393^2 .

It is a cyclic number.

It is not a de Polignac number, because 6640385 - 2⁴ = 6640369 is a prime.

It is a Duffinian 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, 664034 + ... + 664043.

It is an arithmetic number, because the mean of its divisors is an integer number (1992117).

Almost surely, 2^6640385 is an apocalyptic number.

It is an amenable number.

6640385 is a deficient number, since it is larger than the sum of its proper divisors (1328083).

6640385 is a wasteful number, since it uses less digits than its factorization.

6640385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1328082.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 6640385 is about 2576.8944487503. The cubic root of 6640385 is about 187.9595601112.

The spelling of 6640385 in words is "six million, six hundred forty thousand, three hundred eighty-five".