18555661 has 8 divisors (see below), whose sum is σ = 19080864. Its totient is φ = 18034800.

The previous prime is 18555643. The next prime is 18555683. The reversal of 18555661 is 16655581.

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 18555661 - 2⁵ = 18555629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18555661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18585661) 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 7 ways as a sum of consecutive naturals, for example, 8811 + ... + 10711.

It is an arithmetic number, because the mean of its divisors is an integer number (2385108).

Almost surely, 2^18555661 is an apocalyptic number.

It is an amenable number.

18555661 is a deficient number, since it is larger than the sum of its proper divisors (525203).

18555661 is a wasteful number, since it uses less digits than its factorization.

18555661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2171.

The product of its digits is 36000, while the sum is 37.

The square root of 18555661 is about 4307.6282337268. The cubic root of 18555661 is about 264.7436039131.

The spelling of 18555661 in words is "eighteen million, five hundred fifty-five thousand, six hundred sixty-one".