16396656561 has 12 divisors (see below), whose sum is σ = 23686203060. Its totient is φ = 10930115040.

The previous prime is 16396656559. The next prime is 16396656593. The reversal of 16396656561 is 16565669361.

16396656561 is a `hidden beast` number, since 16 + 3 + 9 + 6 + 6 + 565 + 61 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12607022961 + 3789633600 = 112281^2 + 61560^2 .

It is not a de Polignac number, because 16396656561 - 2¹ = 16396656559 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 16396656498 and 16396656507.

It is not an unprimeable number, because it can be changed into a prime (16396656061) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30691 + ... + 183671.

It is an arithmetic number, because the mean of its divisors is an integer number (1973850255).

Almost surely, 2^16396656561 is an apocalyptic number.

It is an amenable number.

16396656561 is a deficient number, since it is larger than the sum of its proper divisors (7289546499).

16396656561 is a wasteful number, since it uses less digits than its factorization.

16396656561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164896 (or 164893 counting only the distinct ones).

The product of its digits is 5248800, while the sum is 54.

The spelling of 16396656561 in words is "sixteen billion, three hundred ninety-six million, six hundred fifty-six thousand, five hundred sixty-one".