16685609 has 2 divisors, whose sum is σ = 16685610. Its totient is φ = 16685608.

The previous prime is 16685593. The next prime is 16685621. The reversal of 16685609 is 90658661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12673600 + 4012009 = 3560^2 + 2003^2 .

It is an emirp because it is prime and its reverse (90658661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16685609 - 2⁴ = 16685593 is a prime.

It is not a weakly prime, because it can be changed into another prime (16685909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8342804 + 8342805.

It is an arithmetic number, because the mean of its divisors is an integer number (8342805).

Almost surely, 2^16685609 is an apocalyptic number.

It is an amenable number.

16685609 is a deficient number, since it is larger than the sum of its proper divisors (1).

16685609 is an equidigital number, since it uses as much as digits as its factorization.

16685609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 41.

The square root of 16685609 is about 4084.8021983935. The cubic root of 16685609 is about 255.5332120842.

The spelling of 16685609 in words is "sixteen million, six hundred eighty-five thousand, six hundred nine".