18863561 has 4 divisors (see below), whose sum is σ = 19856400. Its totient is φ = 17870724.

The previous prime is 18863527. The next prime is 18863563. The reversal of 18863561 is 16536881.

It is a happy number.

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 18863561 - 2¹⁴ = 18847177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18863563) 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, 496391 + ... + 496428.

It is an arithmetic number, because the mean of its divisors is an integer number (4964100).

Almost surely, 2^18863561 is an apocalyptic number.

It is an amenable number.

18863561 is a deficient number, since it is larger than the sum of its proper divisors (992839).

18863561 is an equidigital number, since it uses as much as digits as its factorization.

18863561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 992838.

The product of its digits is 34560, while the sum is 38.

The square root of 18863561 is about 4343.2201187598. The cubic root of 18863561 is about 266.1999034373.

The spelling of 18863561 in words is "eighteen million, eight hundred sixty-three thousand, five hundred sixty-one".