11556661 has 4 divisors (see below), whose sum is σ = 11563552. Its totient is φ = 11549772.

The previous prime is 11556653. The next prime is 11556683. The reversal of 11556661 is 16665511.

11556661 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 11556661 - 2³ = 11556653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11556631) 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, 886 + ... + 4888.

It is an arithmetic number, because the mean of its divisors is an integer number (2890888).

Almost surely, 2^11556661 is an apocalyptic number.

It is an amenable number.

11556661 is a deficient number, since it is larger than the sum of its proper divisors (6891).

11556661 is an equidigital number, since it uses as much as digits as its factorization.

11556661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6890.

The product of its digits is 5400, while the sum is 31.

The square root of 11556661 is about 3399.5089351258. The cubic root of 11556661 is about 226.0879718605.

The spelling of 11556661 in words is "eleven million, five hundred fifty-six thousand, six hundred sixty-one".