16785409 has 9 divisors (see below), whose sum is σ = 17905161. Its totient is φ = 15732480.

The previous prime is 16785407. The next prime is 16785413. The reversal of 16785409 is 90458761.

The square root of 16785409 is 4097.

It is a perfect power (a square), and thus also a powerful number.

16785409 is nontrivially palindromic in base 4, base 8 and base 16.

It can be written as a sum of positive squares in 4 ways, for example, as 4730625 + 12054784 = 2175^2 + 3472^2 .

It is not a de Polignac number, because 16785409 - 2¹ = 16785407 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16785407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (3) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 69529 + ... + 69769.

It is a Proth number, since it is equal to 2049 ⋅ 2¹³ + 1 and 2049 < 2¹³.

Almost surely, 2^16785409 is an apocalyptic number.

16785409 is the 4097-th square number.

16785409 is the 2049-th centered octagonal number.

It is an amenable number.

16785409 is a deficient number, since it is larger than the sum of its proper divisors (1119752).

16785409 is an frugal number, since it uses more digits than its factorization.

16785409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516 (or 258 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 40.

The cubic root of 16785409 is about 256.0416649714.

The spelling of 16785409 in words is "sixteen million, seven hundred eighty-five thousand, four hundred nine".