199999999999991 has 4 divisors (see below), whose sum is σ = 202061855670192. Its totient is φ = 197938144329792.

The previous prime is 199999999999903. The next prime is 199999999999997.

199999999999991 is nontrivially palindromic in base 10.

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 199999999999991 - 2³⁰ = 199998926258167 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 (199999999999997) 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, 1030927834955 + ... + 1030927835148.

It is an arithmetic number, because the mean of its divisors is an integer number (50515463917548).

Almost surely, 2^{199999999999991} is an apocalyptic number.

199999999999991 is a deficient number, since it is larger than the sum of its proper divisors (2061855670201).

199999999999991 is an equidigital number, since it uses as much as digits as its factorization.

199999999999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2061855670200.

The product of its digits is 2541865828329, while the sum is 119.

The spelling of 199999999999991 in words is "one hundred ninety-nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-one".