199993666 has 4 divisors (see below), whose sum is σ = 299990502. Its totient is φ = 99996832.

The previous prime is 199993663. The next prime is 199993667. The reversal of 199993666 is 666399991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 119443041 + 80550625 = 10929^2 + 8975^2 .

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 199993666.

It is not an unprimeable number, because it can be changed into a prime (199993663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49998415 + ... + 49998418.

Almost surely, 2^199993666 is an apocalyptic number.

199993666 is a deficient number, since it is larger than the sum of its proper divisors (99996836).

199993666 is an equidigital number, since it uses as much as digits as its factorization.

199993666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99996835.

The product of its digits is 4251528, while the sum is 58.

The square root of 199993666 is about 14141.9116812403. The cubic root of 199993666 is about 584.7973740013.

It can be divided in two parts, 1999936 and 66, that added together give a palindrome (2000002).

The spelling of 199993666 in words is "one hundred ninety-nine million, nine hundred ninety-three thousand, six hundred sixty-six".