6640015 has 4 divisors (see below), whose sum is σ = 7968024. Its totient is φ = 5312008.

The previous prime is 6640009. The next prime is 6640021. The reversal of 6640015 is 5100466.

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

It is an interprime number because it is at equal distance from previous prime (6640009) and next prime (6640021).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6640015 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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, 663997 + ... + 664006.

It is an arithmetic number, because the mean of its divisors is an integer number (1992006).

Almost surely, 2^6640015 is an apocalyptic number.

6640015 is a deficient number, since it is larger than the sum of its proper divisors (1328009).

6640015 is a wasteful number, since it uses less digits than its factorization.

6640015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1328008.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 6640015 is about 2576.8226559079. The cubic root of 6640015 is about 187.9560690320.

The spelling of 6640015 in words is "six million, six hundred forty thousand, fifteen".