16539509 has 6 divisors (see below), whose sum is σ = 19239894. Its totient is φ = 14176680.

The previous prime is 16539503. The next prime is 16539511. The reversal of 16539509 is 90593561.

It can be written as a sum of positive squares in only one way, i.e., 15038884 + 1500625 = 3878^2 + 1225^2 .

It is not a de Polignac number, because 16539509 - 2¹⁶ = 16473973 is a prime.

It is a super-2 number, since 2×16539509² = 547110715922162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16539503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 168722 + ... + 168819.

It is an arithmetic number, because the mean of its divisors is an integer number (3206649).

Almost surely, 2^16539509 is an apocalyptic number.

It is an amenable number.

16539509 is a deficient number, since it is larger than the sum of its proper divisors (2700385).

16539509 is an equidigital number, since it uses as much as digits as its factorization.

16539509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337555 (or 337548 counting only the distinct ones).

The product of its (nonzero) digits is 36450, while the sum is 38.

The square root of 16539509 is about 4066.8795162876. The cubic root of 16539509 is about 254.7852042288.

The spelling of 16539509 in words is "sixteen million, five hundred thirty-nine thousand, five hundred nine".