6440665 has 16 divisors (see below), whose sum is σ = 9636480. Its totient is φ = 4014720.

The previous prime is 6440647. The next prime is 6440683. The reversal of 6440665 is 5660446.

It is an interprime number because it is at equal distance from previous prime (6440647) and next prime (6440683).

It is not a de Polignac number, because 6440665 - 2⁷ = 6440537 is a prime.

It is an Ulam number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7980 + ... + 8749.

It is an arithmetic number, because the mean of its divisors is an integer number (602280).

Almost surely, 2^6440665 is an apocalyptic number.

It is an amenable number.

6440665 is a deficient number, since it is larger than the sum of its proper divisors (3195815).

6440665 is a wasteful number, since it uses less digits than its factorization.

6440665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16752.

The product of its (nonzero) digits is 17280, while the sum is 31.

The square root of 6440665 is about 2537.8465280627. The cubic root of 6440665 is about 186.0559530280.

The spelling of 6440665 in words is "six million, four hundred forty thousand, six hundred sixty-five".