6663645 has 24 divisors (see below), whose sum is σ = 11610456. Its totient is φ = 3535488.

The previous prime is 6663617. The next prime is 6663647. The reversal of 6663645 is 5463666.

It can be written as a sum of positive squares in 4 ways, for example, as 1159929 + 5503716 = 1077^2 + 2346^2 .

It is not a de Polignac number, because 6663645 - 2⁸ = 6663389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6663647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16587 + ... + 16983.

It is an arithmetic number, because the mean of its divisors is an integer number (483769).

Almost surely, 2^6663645 is an apocalyptic number.

It is an amenable number.

6663645 is a deficient number, since it is larger than the sum of its proper divisors (4946811).

6663645 is a wasteful number, since it uses less digits than its factorization.

6663645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 781 (or 778 counting only the distinct ones).

The product of its digits is 77760, while the sum is 36.

The square root of 6663645 is about 2581.4036879186. The cubic root of 6663645 is about 188.1787665071.

The spelling of 6663645 in words is "six million, six hundred sixty-three thousand, six hundred forty-five".