199997866 has 4 divisors (see below), whose sum is σ = 299996802. Its totient is φ = 99998932.

The previous prime is 199997851. The next prime is 199997867. The reversal of 199997866 is 668799991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 668799991 = 4639 ⋅144169.

It can be written as a sum of positive squares in only one way, i.e., 192626641 + 7371225 = 13879^2 + 2715^2 .

It is a junction number, because it is equal to n+sod(n) for n = 199997798 and 199997807.

It is not an unprimeable number, because it can be changed into a prime (199997867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49999465 + ... + 49999468.

Almost surely, 2^199997866 is an apocalyptic number.

199997866 is a deficient number, since it is larger than the sum of its proper divisors (99998936).

199997866 is an equidigital number, since it uses as much as digits as its factorization.

199997866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99998935.

The product of its digits is 13226976, while the sum is 64.

The square root of 199997866 is about 14142.0601752361. The cubic root of 199997866 is about 584.8014676839.

The spelling of 199997866 in words is "one hundred ninety-nine million, nine hundred ninety-seven thousand, eight hundred sixty-six".