199997851 has 2 divisors, whose sum is σ = 199997852. Its totient is φ = 199997850.

The previous prime is 199997797. The next prime is 199997867. The reversal of 199997851 is 158799991.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 199997851 - 2⁷ = 199997723 is a prime.

It is not a weakly prime, because it can be changed into another prime (199937851) 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 as a sum of consecutive naturals, namely, 99998925 + 99998926.

It is an arithmetic number, because the mean of its divisors is an integer number (99998926).

Almost surely, 2^199997851 is an apocalyptic number.

199997851 is a deficient number, since it is larger than the sum of its proper divisors (1).

199997851 is an equidigital number, since it uses as much as digits as its factorization.

199997851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1837080, while the sum is 58.

The square root of 199997851 is about 14142.0596449032. The cubic root of 199997851 is about 584.8014530637.

The spelling of 199997851 in words is "one hundred ninety-nine million, nine hundred ninety-seven thousand, eight hundred fifty-one".