6668561 has 4 divisors (see below), whose sum is σ = 6730992. Its totient is φ = 6606132.

The previous prime is 6668549. The next prime is 6668567. The reversal of 6668561 is 1658666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6668561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6668567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31055 + ... + 31268.

It is an arithmetic number, because the mean of its divisors is an integer number (1682748).

Almost surely, 2^6668561 is an apocalyptic number.

It is an amenable number.

6668561 is a deficient number, since it is larger than the sum of its proper divisors (62431).

6668561 is a wasteful number, since it uses less digits than its factorization.

6668561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62430.

The product of its digits is 51840, while the sum is 38.

The square root of 6668561 is about 2582.3557074888. The cubic root of 6668561 is about 188.2250304472.

The spelling of 6668561 in words is "six million, six hundred sixty-eight thousand, five hundred sixty-one".