11985561 has 72 divisors (see below), whose sum is σ = 22823424. Its totient is φ = 5909760.

The previous prime is 11985559. The next prime is 11985593. The reversal of 11985561 is 16558911.

11985561 is a `hidden beast` number, since 1 + 1 + 98 + 5 + 561 = 666.

It is not a de Polignac number, because 11985561 - 2¹ = 11985559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (11985551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 386616 + ... + 386646.

It is an arithmetic number, because the mean of its divisors is an integer number (316992).

Almost surely, 2^11985561 is an apocalyptic number.

It is an amenable number.

11985561 is a deficient number, since it is larger than the sum of its proper divisors (10837863).

11985561 is a wasteful number, since it uses less digits than its factorization.

11985561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 77 counting only the distinct ones).

The product of its digits is 10800, while the sum is 36.

The square root of 11985561 is about 3462.0168977057. The cubic root of 11985561 is about 228.8509864957.

The spelling of 11985561 in words is "eleven million, nine hundred eighty-five thousand, five hundred sixty-one".