18995561 has 8 divisors (see below), whose sum is σ = 20490624. Its totient is φ = 17505360.

The previous prime is 18995533. The next prime is 18995597. The reversal of 18995561 is 16559981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18995561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18995521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14816 + ... + 16046.

It is an arithmetic number, because the mean of its divisors is an integer number (2561328).

Almost surely, 2^18995561 is an apocalyptic number.

It is an amenable number.

18995561 is a deficient number, since it is larger than the sum of its proper divisors (1495063).

18995561 is a wasteful number, since it uses less digits than its factorization.

18995561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2431.

The product of its digits is 97200, while the sum is 44.

The square root of 18995561 is about 4358.3897255753. The cubic root of 18995561 is about 266.8193824906.

The spelling of 18995561 in words is "eighteen million, nine hundred ninety-five thousand, five hundred sixty-one".