18855561 has 8 divisors (see below), whose sum is σ = 26233920. Its totient is φ = 12023792.

The previous prime is 18855559. The next prime is 18855569. The reversal of 18855561 is 16555881.

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

It is a cyclic number.

It is not a de Polignac number, because 18855561 - 2¹ = 18855559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18855569) 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, 136566 + ... + 136703.

It is an arithmetic number, because the mean of its divisors is an integer number (3279240).

Almost surely, 2^18855561 is an apocalyptic number.

It is an amenable number.

18855561 is a deficient number, since it is larger than the sum of its proper divisors (7378359).

18855561 is a wasteful number, since it uses less digits than its factorization.

18855561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273295.

The product of its digits is 48000, while the sum is 39.

The square root of 18855561 is about 4342.2990454366. The cubic root of 18855561 is about 266.1622664936.

The spelling of 18855561 in words is "eighteen million, eight hundred fifty-five thousand, five hundred sixty-one".