199685987 has 4 divisors (see below), whose sum is σ = 199721040. Its totient is φ = 199650936.

The previous prime is 199685971. The next prime is 199686013. The reversal of 199685987 is 789586991.

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

It is a cyclic number.

It is not a de Polignac number, because 199685987 - 2⁴ = 199685971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199685957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6788 + ... + 21105.

It is an arithmetic number, because the mean of its divisors is an integer number (49930260).

Almost surely, 2^199685987 is an apocalyptic number.

199685987 is a deficient number, since it is larger than the sum of its proper divisors (35053).

199685987 is an equidigital number, since it uses as much as digits as its factorization.

199685987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35052.

The product of its digits is 9797760, while the sum is 62.

The square root of 199685987 is about 14131.0292264930. The cubic root of 199685987 is about 584.4973274641.

The spelling of 199685987 in words is "one hundred ninety-nine million, six hundred eighty-five thousand, nine hundred eighty-seven".