199391897 has 4 divisors (see below), whose sum is σ = 204255156. Its totient is φ = 194528640.

The previous prime is 199391887. The next prime is 199391957. The reversal of 199391897 is 798193991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 798193991 = 7 ⋅114027713.

It can be written as a sum of positive squares in 2 ways, for example, as 20394256 + 178997641 = 4516^2 + 13379^2 .

It is a cyclic number.

It is not a de Polignac number, because 199391897 - 2⁸ = 199391641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199391887) 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, 2431568 + ... + 2431649.

It is an arithmetic number, because the mean of its divisors is an integer number (51063789).

Almost surely, 2^199391897 is an apocalyptic number.

It is an amenable number.

199391897 is a deficient number, since it is larger than the sum of its proper divisors (4863259).

199391897 is an equidigital number, since it uses as much as digits as its factorization.

199391897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4863258.

The product of its digits is 1102248, while the sum is 56.

The square root of 199391897 is about 14120.6195685600. The cubic root of 199391897 is about 584.2102446005.

The spelling of 199391897 in words is "one hundred ninety-nine million, three hundred ninety-one thousand, eight hundred ninety-seven".