18144220561 has 4 divisors (see below), whose sum is σ = 18362825712. Its totient is φ = 17925615412.

The previous prime is 18144220559. The next prime is 18144220571. The reversal of 18144220561 is 16502244181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16502244181 = 367 ⋅44965243.

It is a cyclic number.

It is not a de Polignac number, because 18144220561 - 2¹ = 18144220559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18144220541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109302451 + ... + 109302616.

It is an arithmetic number, because the mean of its divisors is an integer number (4590706428).

Almost surely, 2^18144220561 is an apocalyptic number.

It is an amenable number.

18144220561 is a deficient number, since it is larger than the sum of its proper divisors (218605151).

18144220561 is an equidigital number, since it uses as much as digits as its factorization.

18144220561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218605150.

The product of its (nonzero) digits is 15360, while the sum is 34.

The spelling of 18144220561 in words is "eighteen billion, one hundred forty-four million, two hundred twenty thousand, five hundred sixty-one".