18919177209 has 135 divisors (see below), whose sum is σ = 32128551741. Its totient is φ = 11091790080.

The previous prime is 18919177201. The next prime is 18919177231. The reversal of 18919177209 is 90277191981.

The square root of 18919177209 is 137547.

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

18919177209 is a `hidden beast` number, since 189 + 191 + 77 + 209 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1870130025 + 17049047184 = 43245^2 + 130572^2 .

It is not a de Polignac number, because 18919177209 - 2³ = 18919177201 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18919177201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 610296024 + ... + 610296054.

Almost surely, 2^18919177209 is an apocalyptic number.

18919177209 is the 137547-th square number.

18919177209 is the 68774-th centered octagonal number.

It is an amenable number.

18919177209 is a deficient number, since it is larger than the sum of its proper divisors (13209374532).

18919177209 is an equidigital number, since it uses as much as digits as its factorization.

18919177209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166 (or 80 counting only the distinct ones).

The product of its (nonzero) digits is 571536, while the sum is 54.

The spelling of 18919177209 in words is "eighteen billion, nine hundred nineteen million, one hundred seventy-seven thousand, two hundred nine".