11643561 has 16 divisors (see below), whose sum is σ = 18158400. Its totient is φ = 7353504.

The previous prime is 11643559. The next prime is 11643563. The reversal of 11643561 is 16534611.

11643561 is a `hidden beast` number, since 11 + 643 + 5 + 6 + 1 = 666.

11643561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (11643559) and next prime (11643563).

It is not a de Polignac number, because 11643561 - 2¹ = 11643559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (11643563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10836 + ... + 11861.

It is an arithmetic number, because the mean of its divisors is an integer number (1134900).

Almost surely, 2^11643561 is an apocalyptic number.

It is an amenable number.

11643561 is a deficient number, since it is larger than the sum of its proper divisors (6514839).

11643561 is a wasteful number, since it uses less digits than its factorization.

11643561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22725 (or 22719 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 11643561 is about 3412.2662557309. The cubic root of 11643561 is about 226.6532448319.

The spelling of 11643561 in words is "eleven million, six hundred forty-three thousand, five hundred sixty-one".