199999999 has 8 divisors (see below), whose sum is σ = 202517280. Its totient is φ = 197488896.

The previous prime is 199999991. The next prime is 200000033. The reversal of 199999999 is 999999991.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 199999999 - 2³ = 199999991 is a prime.

It is a fibodiv number, since the Fibonacci-like sequence with seeds 1 and 99999999 contains 199999999 itself.

It is a Duffinian number.

199999999 is a modest number, since divided by 99999 gives 1999 as remainder.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199999991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128007 + ... + 129559.

It is an arithmetic number, because the mean of its divisors is an integer number (25314660).

Almost surely, 2^199999999 is an apocalyptic number.

199999999 is a deficient number, since it is larger than the sum of its proper divisors (2517281).

199999999 is a wasteful number, since it uses less digits than its factorization.

199999999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3089.

The product of its digits is 43046721, while the sum is 73.

The square root of 199999999 is about 14142.1355883756. The cubic root of 199999999 is about 584.8035466679.

It can be divided in two parts, 19999 and 9999, that multiplied together give a triangular number (199970001 = T₁₉₉₉₈).

The spelling of 199999999 in words is "one hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-nine".