18604561 has 4 divisors (see below), whose sum is σ = 18859492. Its totient is φ = 18349632.

The previous prime is 18604543. The next prime is 18604567. The reversal of 18604561 is 16540681.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15563025 + 3041536 = 3945^2 + 1744^2 .

It is a cyclic number.

It is not a de Polignac number, because 18604561 - 2¹⁹ = 18080273 is a prime.

It is a super-2 number, since 2×18604561² = 692259380005442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18604567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 127356 + ... + 127501.

It is an arithmetic number, because the mean of its divisors is an integer number (4714873).

Almost surely, 2^18604561 is an apocalyptic number.

It is an amenable number.

18604561 is a deficient number, since it is larger than the sum of its proper divisors (254931).

18604561 is an equidigital number, since it uses as much as digits as its factorization.

18604561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254930.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 18604561 is about 4313.3004764333. The cubic root of 18604561 is about 264.9759607955.

The spelling of 18604561 in words is "eighteen million, six hundred four thousand, five hundred sixty-one".