18181016569 has 3 divisors (see below), whose sum is σ = 18181151407. Its totient is φ = 18180881732.

The previous prime is 18181016531. The next prime is 18181016573. The reversal of 18181016569 is 96561018181.

It is a happy number.

The square root of 18181016569 is 134837.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 6039621225 + 12141395344 = 77715^2 + 110188^2 .

It is not a de Polignac number, because 18181016569 - 2¹¹ = 18181014521 is a prime.

It is a super-2 number, since 2×18181016569² (a number of 21 digits) contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18181016669) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 67419 + ... + 202255.

Almost surely, 2^18181016569 is an apocalyptic number.

18181016569 is the 134837-th square number.

18181016569 is the 67419-th centered octagonal number.

It is an amenable number.

18181016569 is a deficient number, since it is larger than the sum of its proper divisors (134838).

18181016569 is an frugal number, since it uses more digits than its factorization.

18181016569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269674 (or 134837 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 46.

The spelling of 18181016569 in words is "eighteen billion, one hundred eighty-one million, sixteen thousand, five hundred sixty-nine".