11556015661 has 4 divisors (see below), whose sum is σ = 11563873024. Its totient is φ = 11548158300.

The previous prime is 11556015629. The next prime is 11556015677. The reversal of 11556015661 is 16651065511.

11556015661 is digitally balanced in base 2, because in such base 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 an emirpimes, since its reverse is a distinct semiprime: 16651065511 = 19 ⋅876371869.

It is a cyclic number.

It is not a de Polignac number, because 11556015661 - 2⁵ = 11556015629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 11556015661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11556615661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3926475 + ... + 3929416.

It is an arithmetic number, because the mean of its divisors is an integer number (2890968256).

Almost surely, 2^11556015661 is an apocalyptic number.

It is an amenable number.

11556015661 is a deficient number, since it is larger than the sum of its proper divisors (7857363).

11556015661 is an equidigital number, since it uses as much as digits as its factorization.

11556015661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7857362.

The product of its (nonzero) digits is 27000, while the sum is 37.

The spelling of 11556015661 in words is "eleven billion, five hundred fifty-six million, fifteen thousand, six hundred sixty-one".