199564891 has 2 divisors, whose sum is σ = 199564892. Its totient is φ = 199564890.

The previous prime is 199564889. The next prime is 199564919. The reversal of 199564891 is 198465991.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (198465991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199564891 - 2¹ = 199564889 is a prime.

It is a super-2 number, since 2×199564891² = 79652291439683762, which contains 22 as substring.

Together with 199564889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (199564811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99782445 + 99782446.

It is an arithmetic number, because the mean of its divisors is an integer number (99782446).

Almost surely, 2^199564891 is an apocalyptic number.

199564891 is a deficient number, since it is larger than the sum of its proper divisors (1).

199564891 is an equidigital number, since it uses as much as digits as its factorization.

199564891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 52.

The square root of 199564891 is about 14126.7438215606. The cubic root of 199564891 is about 584.3791509175.

The spelling of 199564891 in words is "one hundred ninety-nine million, five hundred sixty-four thousand, eight hundred ninety-one".