16618561 has 2 divisors, whose sum is σ = 16618562. Its totient is φ = 16618560.

The previous prime is 16618549. The next prime is 16618577. The reversal of 16618561 is 16581661.

16618561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15366400 + 1252161 = 3920^2 + 1119^2 .

It is a cyclic number.

It is not a de Polignac number, because 16618561 - 2¹¹ = 16616513 is a prime.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (16618531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8309280 + 8309281.

It is an arithmetic number, because the mean of its divisors is an integer number (8309281).

Almost surely, 2^16618561 is an apocalyptic number.

It is an amenable number.

16618561 is a deficient number, since it is larger than the sum of its proper divisors (1).

16618561 is an equidigital number, since it uses as much as digits as its factorization.

16618561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 34.

The square root of 16618561 is about 4076.5869302641. The cubic root of 16618561 is about 255.1904817960.

The spelling of 16618561 in words is "sixteen million, six hundred eighteen thousand, five hundred sixty-one".