18382207561 has 3 divisors (see below), whose sum is σ = 18382343143. Its totient is φ = 18382071980.

The previous prime is 18382207531. The next prime is 18382207567. The reversal of 18382207561 is 16570228381.

The square root of 18382207561 is 135581.

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., 7661675961 + 10720531600 = 87531^2 + 103540^2 .

It is not a de Polignac number, because 18382207561 - 2⁷ = 18382207433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18382207567) 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, 67791 + ... + 203371.

Almost surely, 2^18382207561 is an apocalyptic number.

18382207561 is the 135581-st square number.

18382207561 is the 67791-st centered octagonal number.

It is an amenable number.

18382207561 is a deficient number, since it is larger than the sum of its proper divisors (135582).

18382207561 is an frugal number, since it uses more digits than its factorization.

18382207561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271162 (or 135581 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 43.

The spelling of 18382207561 in words is "eighteen billion, three hundred eighty-two million, two hundred seven thousand, five hundred sixty-one".