6663561 has 4 divisors (see below), whose sum is σ = 8884752. Its totient is φ = 4442372.

The previous prime is 6663557. The next prime is 6663593. The reversal of 6663561 is 1653666.

6663561 is nontrivially palindromic in base 11.

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 not a de Polignac number, because 6663561 - 2² = 6663557 is a prime.

It is a D-number.

It is a Curzon number.

6663561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (6663511) 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, 1110591 + ... + 1110596.

It is an arithmetic number, because the mean of its divisors is an integer number (2221188).

Almost surely, 2^6663561 is an apocalyptic number.

It is an amenable number.

6663561 is a deficient number, since it is larger than the sum of its proper divisors (2221191).

6663561 is a wasteful number, since it uses less digits than its factorization.

6663561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2221190.

The product of its digits is 19440, while the sum is 33.

The square root of 6663561 is about 2581.3874176497. The cubic root of 6663561 is about 188.1779757945.

The spelling of 6663561 in words is "six million, six hundred sixty-three thousand, five hundred sixty-one".