18732561 has 4 divisors (see below), whose sum is σ = 24976752. Its totient is φ = 12488372.

The previous prime is 18732547. The next prime is 18732577. The reversal of 18732561 is 16523781.

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 18732561 - 2¹⁴ = 18716177 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18732541) 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, 3122091 + ... + 3122096.

It is an arithmetic number, because the mean of its divisors is an integer number (6244188).

Almost surely, 2^18732561 is an apocalyptic number.

It is an amenable number.

18732561 is a deficient number, since it is larger than the sum of its proper divisors (6244191).

18732561 is an equidigital number, since it uses as much as digits as its factorization.

18732561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6244190.

The product of its digits is 10080, while the sum is 33.

The square root of 18732561 is about 4328.1128682140. The cubic root of 18732561 is about 265.5822536242.

The spelling of 18732561 in words is "eighteen million, seven hundred thirty-two thousand, five hundred sixty-one".