16809991 has 16 divisors (see below), whose sum is σ = 19549728. Its totient is φ = 14284800.

The previous prime is 16809979. The next prime is 16809997. The reversal of 16809991 is 19990861.

It is a cyclic number.

It is not a de Polignac number, because 16809991 - 2⁹ = 16809479 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16809997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44881 + ... + 45253.

It is an arithmetic number, because the mean of its divisors is an integer number (1221858).

Almost surely, 2^16809991 is an apocalyptic number.

16809991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

16809991 is a deficient number, since it is larger than the sum of its proper divisors (2739737).

16809991 is a wasteful number, since it uses less digits than its factorization.

16809991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642.

The product of its (nonzero) digits is 34992, while the sum is 43.

The square root of 16809991 is about 4099.9989024389. The cubic root of 16809991 is about 256.1665938349.

The spelling of 16809991 in words is "sixteen million, eight hundred nine thousand, nine hundred ninety-one".