561636161 has 2 divisors, whose sum is σ = 561636162. Its totient is φ = 561636160.

The previous prime is 561636151. The next prime is 561636217. The reversal of 561636161 is 161636165.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 560789761 + 846400 = 23681^2 + 920^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561636161 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (561636151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280818080 + 280818081.

It is an arithmetic number, because the mean of its divisors is an integer number (280818081).

Almost surely, 2^561636161 is an apocalyptic number.

It is an amenable number.

561636161 is a deficient number, since it is larger than the sum of its proper divisors (1).

561636161 is an equidigital number, since it uses as much as digits as its factorization.

561636161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 35.

The square root of 561636161 is about 23698.8641288987. The cubic root of 561636161 is about 825.0590277937.

The spelling of 561636161 in words is "five hundred sixty-one million, six hundred thirty-six thousand, one hundred sixty-one".