18216641 has 2 divisors, whose sum is σ = 18216642. Its totient is φ = 18216640.

The previous prime is 18216637. The next prime is 18216661. The reversal of 18216641 is 14661281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13359025 + 4857616 = 3655^2 + 2204^2 .

It is a cyclic number.

It is not a de Polignac number, because 18216641 - 2² = 18216637 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18216661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9108320 + 9108321.

It is an arithmetic number, because the mean of its divisors is an integer number (9108321).

Almost surely, 2^18216641 is an apocalyptic number.

It is an amenable number.

18216641 is a deficient number, since it is larger than the sum of its proper divisors (1).

18216641 is an equidigital number, since it uses as much as digits as its factorization.

18216641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 29.

The square root of 18216641 is about 4268.0957112042. The cubic root of 18216641 is about 263.1213567650.

The spelling of 18216641 in words is "eighteen million, two hundred sixteen thousand, six hundred forty-one".