16539865 has 4 divisors (see below), whose sum is σ = 19847844. Its totient is φ = 13231888.

The previous prime is 16539857. The next prime is 16539871. The reversal of 16539865 is 56893561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56893561 = 2111 ⋅26951.

It can be written as a sum of positive squares in 2 ways, for example, as 10067929 + 6471936 = 3173^2 + 2544^2 .

It is a cyclic number.

It is not a de Polignac number, because 16539865 - 2³ = 16539857 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1653982 + ... + 1653991.

It is an arithmetic number, because the mean of its divisors is an integer number (4961961).

Almost surely, 2^16539865 is an apocalyptic number.

It is an amenable number.

16539865 is a deficient number, since it is larger than the sum of its proper divisors (3307979).

16539865 is an equidigital number, since it uses as much as digits as its factorization.

16539865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3307978.

The product of its digits is 194400, while the sum is 43.

The square root of 16539865 is about 4066.9232842531. The cubic root of 16539865 is about 254.7870322331.

The spelling of 16539865 in words is "sixteen million, five hundred thirty-nine thousand, eight hundred sixty-five".