199919999 has 4 divisors (see below), whose sum is σ = 204173664. Its totient is φ = 195666336.

The previous prime is 199919987. The next prime is 199920001. The reversal of 199919999 is 999919991.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199919999 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199919959) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2126762 + ... + 2126855.

It is an arithmetic number, because the mean of its divisors is an integer number (51043416).

Almost surely, 2^199919999 is an apocalyptic number.

199919999 is a deficient number, since it is larger than the sum of its proper divisors (4253665).

199919999 is an equidigital number, since it uses as much as digits as its factorization.

199919999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4253664.

The product of its digits is 4782969, while the sum is 65.

The square root of 199919999 is about 14139.3068783445. The cubic root of 199919999 is about 584.7255624625.

The spelling of 199919999 in words is "one hundred ninety-nine million, nine hundred nineteen thousand, nine hundred ninety-nine".