18100561 has 4 divisors (see below), whose sum is σ = 18153072. Its totient is φ = 18048052.

The previous prime is 18100547. The next prime is 18100573. The reversal of 18100561 is 16500181.

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.

It is a cyclic number.

It is not a de Polignac number, because 18100561 - 2¹⁵ = 18067793 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (18100501) 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, 25735 + ... + 26428.

It is an arithmetic number, because the mean of its divisors is an integer number (4538268).

Almost surely, 2^18100561 is an apocalyptic number.

It is an amenable number.

18100561 is a deficient number, since it is larger than the sum of its proper divisors (52511).

18100561 is an equidigital number, since it uses as much as digits as its factorization.

18100561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52510.

The product of its (nonzero) digits is 240, while the sum is 22.

The square root of 18100561 is about 4254.4754083200. The cubic root of 18100561 is about 262.5612785133.

The spelling of 18100561 in words is "eighteen million, one hundred thousand, five hundred sixty-one".