16500173209 has 27 divisors (see below), whose sum is σ = 18389766807. Its totient is φ = 14797785600.

The previous prime is 16500173197. The next prime is 16500173231. The reversal of 16500173209 is 90237100561.

The square root of 16500173209 is 128453.

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

It can be written as a sum of positive squares in 13 ways, for example, as 16352015625 + 148157584 = 127875^2 + 12172^2 .

It is a de Polignac number, because none of the positive numbers 2^k-16500173209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16500173269) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 68465329 + ... + 68465569.

Almost surely, 2^16500173209 is an apocalyptic number.

16500173209 is the 128453-rd square number.

16500173209 is the 64227-th centered octagonal number.

It is an amenable number.

16500173209 is a deficient number, since it is larger than the sum of its proper divisors (1889593598).

16500173209 is an frugal number, since it uses more digits than its factorization.

16500173209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 590 (or 295 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 34.

The spelling of 16500173209 in words is "sixteen billion, five hundred million, one hundred seventy-three thousand, two hundred nine".