199791891 has 24 divisors (see below), whose sum is σ = 312298896. Its totient is φ = 122351040.

The previous prime is 199791883. The next prime is 199791901. The reversal of 199791891 is 198197991.

It is a happy number.

199791891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 199791891 - 2³ = 199791883 is a prime.

It is not an unprimeable number, because it can be changed into a prime (199795891) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20641 + ... + 28733.

It is an arithmetic number, because the mean of its divisors is an integer number (13012454).

Almost surely, 2^199791891 is an apocalyptic number.

199791891 is a deficient number, since it is larger than the sum of its proper divisors (112507005).

199791891 is a wasteful number, since it uses less digits than its factorization.

199791891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8323 (or 8320 counting only the distinct ones).

The product of its digits is 367416, while the sum is 54.

The square root of 199791891 is about 14134.7759444570. The cubic root of 199791891 is about 584.6006391120.

The spelling of 199791891 in words is "one hundred ninety-nine million, seven hundred ninety-one thousand, eight hundred ninety-one".