18416561 has 2 divisors, whose sum is σ = 18416562. Its totient is φ = 18416560.

The previous prime is 18416557. The next prime is 18416579. The reversal of 18416561 is 16561481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9265936 + 9150625 = 3044^2 + 3025^2 .

It is a cyclic number.

It is not a de Polignac number, because 18416561 - 2² = 18416557 is a prime.

It is not a weakly prime, because it can be changed into another prime (18416501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9208280 + 9208281.

It is an arithmetic number, because the mean of its divisors is an integer number (9208281).

Almost surely, 2^18416561 is an apocalyptic number.

It is an amenable number.

18416561 is a deficient number, since it is larger than the sum of its proper divisors (1).

18416561 is an equidigital number, since it uses as much as digits as its factorization.

18416561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 32.

The square root of 18416561 is about 4291.4520852504. The cubic root of 18416561 is about 264.0804057580.

The spelling of 18416561 in words is "eighteen million, four hundred sixteen thousand, five hundred sixty-one".