18626561 has 4 divisors (see below), whose sum is σ = 18730800. Its totient is φ = 18522324.

The previous prime is 18626557. The next prime is 18626579. The reversal of 18626561 is 16562681.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16562681 = 193 ⋅85817.

It is a cyclic number.

It is not a de Polignac number, because 18626561 - 2² = 18626557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18626551) 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, 51851 + ... + 52208.

It is an arithmetic number, because the mean of its divisors is an integer number (4682700).

Almost surely, 2^18626561 is an apocalyptic number.

It is an amenable number.

18626561 is a deficient number, since it is larger than the sum of its proper divisors (104239).

18626561 is a wasteful number, since it uses less digits than its factorization.

18626561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104238.

The product of its digits is 17280, while the sum is 35.

The square root of 18626561 is about 4315.8499742229. The cubic root of 18626561 is about 265.0803648509.

The spelling of 18626561 in words is "eighteen million, six hundred twenty-six thousand, five hundred sixty-one".