18044817561 has 9 divisors (see below), whose sum is σ = 26065318591. Its totient is φ = 12029609712.

The previous prime is 18044817529. The next prime is 18044817599. The reversal of 18044817561 is 16571844081.

The square root of 18044817561 is 134331.

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

18044817561 is a `hidden beast` number, since 1 + 8 + 0 + 4 + 4 + 81 + 7 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 17634512025 + 410305536 = 132795^2 + 20256^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 18044817561 - 2⁵ = 18044817529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18044817061) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 380605 + ... + 425381.

Almost surely, 2^18044817561 is an apocalyptic number.

18044817561 is the 134331-st square number.

18044817561 is the 67166-th centered octagonal number.

It is an amenable number.

18044817561 is a deficient number, since it is larger than the sum of its proper divisors (8020501030).

18044817561 is an frugal number, since it uses more digits than its factorization.

18044817561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89560 (or 44780 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 18044817561 in words is "eighteen billion, forty-four million, eight hundred seventeen thousand, five hundred sixty-one".