18909117169 has 4 divisors (see below), whose sum is σ = 18917951220. Its totient is φ = 18900283120.

The previous prime is 18909117137. The next prime is 18909117191. The reversal of 18909117169 is 96171190981.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17501967025 + 1407150144 = 132295^2 + 37512^2 .

It is a cyclic number.

It is not a de Polignac number, because 18909117169 - 2⁵ = 18909117137 is a prime.

It is a super-2 number, since 2×18909117169² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18909117869) 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 3 ways as a sum of consecutive naturals, for example, 4413814 + ... + 4418095.

It is an arithmetic number, because the mean of its divisors is an integer number (4729487805).

Almost surely, 2^18909117169 is an apocalyptic number.

It is an amenable number.

18909117169 is a deficient number, since it is larger than the sum of its proper divisors (8834051).

18909117169 is an equidigital number, since it uses as much as digits as its factorization.

18909117169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8834050.

The product of its (nonzero) digits is 244944, while the sum is 52.

The spelling of 18909117169 in words is "eighteen billion, nine hundred nine million, one hundred seventeen thousand, one hundred sixty-nine".