18406077561 has 27 divisors (see below), whose sum is σ = 27275553487. Its totient is φ = 11960579040.

The previous prime is 18406077439. The next prime is 18406077601. The reversal of 18406077561 is 16577060481.

The square root of 18406077561 is 135669.

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

18406077561 is a `hidden beast` number, since 1 + 84 + 0 + 6 + 0 + 7 + 7 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 886907961 + 17519169600 = 29781^2 + 132360^2 .

It is not a de Polignac number, because 18406077561 - 2⁹ = 18406077049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18406077061) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 16686736 + ... + 16687838.

Almost surely, 2^18406077561 is an apocalyptic number.

18406077561 is the 135669-th square number.

18406077561 is the 67835-th centered octagonal number.

It is an amenable number.

18406077561 is a deficient number, since it is larger than the sum of its proper divisors (8869475926).

18406077561 is an frugal number, since it uses more digits than its factorization.

18406077561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2294 (or 1147 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 45.

The spelling of 18406077561 in words is "eighteen billion, four hundred six million, seventy-seven thousand, five hundred sixty-one".