16645609 has 4 divisors (see below), whose sum is σ = 16653780. Its totient is φ = 16637440.

The previous prime is 16645591. The next prime is 16645627. The reversal of 16645609 is 90654661.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90654661 = 23 ⋅3941507.

It is an interprime number because it is at equal distance from previous prime (16645591) and next prime (16645627).

It can be written as a sum of positive squares in 2 ways, for example, as 13505625 + 3139984 = 3675^2 + 1772^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16645609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16645639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1737 + ... + 6025.

It is an arithmetic number, because the mean of its divisors is an integer number (4163445).

Almost surely, 2^16645609 is an apocalyptic number.

It is an amenable number.

16645609 is a deficient number, since it is larger than the sum of its proper divisors (8171).

16645609 is an equidigital number, since it uses as much as digits as its factorization.

16645609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8170.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 16645609 is about 4079.9030625739. The cubic root of 16645609 is about 255.3288542019.

The spelling of 16645609 in words is "sixteen million, six hundred forty-five thousand, six hundred nine".