18002561 has 2 divisors, whose sum is σ = 18002562. Its totient is φ = 18002560.

The previous prime is 18002527. The next prime is 18002573. The reversal of 18002561 is 16520081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12390400 + 5612161 = 3520^2 + 2369^2 .

It is a cyclic number.

It is not a de Polignac number, because 18002561 - 2⁶ = 18002497 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18002161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9001280 + 9001281.

It is an arithmetic number, because the mean of its divisors is an integer number (9001281).

Almost surely, 2^18002561 is an apocalyptic number.

It is an amenable number.

18002561 is a deficient number, since it is larger than the sum of its proper divisors (1).

18002561 is an equidigital number, since it uses as much as digits as its factorization.

18002561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 18002561 is about 4242.9424931290. The cubic root of 18002561 is about 262.0865679402.

The spelling of 18002561 in words is "eighteen million, two thousand, five hundred sixty-one".