18199661 has 2 divisors, whose sum is σ = 18199662. Its totient is φ = 18199660.

The previous prime is 18199637. The next prime is 18199691. The reversal of 18199661 is 16699181.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17056900 + 1142761 = 4130^2 + 1069^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18199661 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18199631) 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, 9099830 + 9099831.

It is an arithmetic number, because the mean of its divisors is an integer number (9099831).

Almost surely, 2^18199661 is an apocalyptic number.

It is an amenable number.

18199661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18199661 is an equidigital number, since it uses as much as digits as its factorization.

18199661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 41.

The square root of 18199661 is about 4266.1060699425. The cubic root of 18199661 is about 263.0395782505.

The spelling of 18199661 in words is "eighteen million, one hundred ninety-nine thousand, six hundred sixty-one".