16666891 has 2 divisors, whose sum is σ = 16666892. Its totient is φ = 16666890.

The previous prime is 16666883. The next prime is 16666907. The reversal of 16666891 is 19866661.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (19866661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16666891 - 2³ = 16666883 is a prime.

It is not a weakly prime, because it can be changed into another prime (16666841) 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 as a sum of consecutive naturals, namely, 8333445 + 8333446.

It is an arithmetic number, because the mean of its divisors is an integer number (8333446).

Almost surely, 2^16666891 is an apocalyptic number.

16666891 is a deficient number, since it is larger than the sum of its proper divisors (1).

16666891 is an equidigital number, since it uses as much as digits as its factorization.

16666891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 43.

The square root of 16666891 is about 4082.5103796561. The cubic root of 16666891 is about 255.4376235177.

The spelling of 16666891 in words is "sixteen million, six hundred sixty-six thousand, eight hundred ninety-one".