9966561 has 16 divisors (see below), whose sum is σ = 14684160. Its totient is φ = 5962320.

The previous prime is 9966559. The next prime is 9966577. The reversal of 9966561 is 1656699.

It is not a de Polignac number, because 9966561 - 2¹ = 9966559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9966511) 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, 696 + ... + 4518.

It is an arithmetic number, because the mean of its divisors is an integer number (917760).

Almost surely, 2^9966561 is an apocalyptic number.

It is an amenable number.

9966561 is a deficient number, since it is larger than the sum of its proper divisors (4717599).

9966561 is a wasteful number, since it uses less digits than its factorization.

9966561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3916.

The product of its digits is 87480, while the sum is 42.

The square root of 9966561 is about 3156.9860626870. The cubic root of 9966561 is about 215.2030603642.

It can be divided in two parts, 996 and 6561, that added together give a palindrome (7557).

The spelling of 9966561 in words is "nine million, nine hundred sixty-six thousand, five hundred sixty-one".