11956561 has 4 divisors (see below), whose sum is σ = 11966272. Its totient is φ = 11946852.

The previous prime is 11956531. The next prime is 11956577. The reversal of 11956561 is 16565911.

11956561 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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16565911 = 23 ⋅720257.

It is a cyclic number.

It is not a de Polignac number, because 11956561 - 2⁷ = 11956433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11956531) 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, 2685 + ... + 5578.

It is an arithmetic number, because the mean of its divisors is an integer number (2991568).

Almost surely, 2^11956561 is an apocalyptic number.

It is an amenable number.

11956561 is a deficient number, since it is larger than the sum of its proper divisors (9711).

11956561 is an equidigital number, since it uses as much as digits as its factorization.

11956561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9710.

The product of its digits is 8100, while the sum is 34.

The square root of 11956561 is about 3457.8260511483. The cubic root of 11956561 is about 228.6662631587. Note that the first 3 decimals are identical.

The spelling of 11956561 in words is "eleven million, nine hundred fifty-six thousand, five hundred sixty-one".