16191891 has 6 divisors (see below), whose sum is σ = 23388300. Its totient is φ = 10794588.

The previous prime is 16191887. The next prime is 16191913. The reversal of 16191891 is 19819161.

It is not a de Polignac number, because 16191891 - 2² = 16191887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16191491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 899541 + ... + 899558.

It is an arithmetic number, because the mean of its divisors is an integer number (3898050).

Almost surely, 2^16191891 is an apocalyptic number.

16191891 is a deficient number, since it is larger than the sum of its proper divisors (7196409).

16191891 is a wasteful number, since it uses less digits than its factorization.

16191891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1799105 (or 1799102 counting only the distinct ones).

The product of its digits is 3888, while the sum is 36.

The square root of 16191891 is about 4023.9148847857. The cubic root of 16191891 is about 252.9875740537.

The spelling of 16191891 in words is "sixteen million, one hundred ninety-one thousand, eight hundred ninety-one".