18861665 has 8 divisors (see below), whose sum is σ = 22657320. Its totient is φ = 15073792.

The previous prime is 18861643. The next prime is 18861673. The reversal of 18861665 is 56616881.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 16 + 18861649 = 4^2 + 4343^2 .

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 18861665 - 2¹⁰ = 18860641 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8447 + ... + 10443.

It is an arithmetic number, because the mean of its divisors is an integer number (2832165).

Almost surely, 2^18861665 is an apocalyptic number.

It is an amenable number.

18861665 is a deficient number, since it is larger than the sum of its proper divisors (3795655).

18861665 is a wasteful number, since it uses less digits than its factorization.

18861665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3891.

The product of its digits is 69120, while the sum is 41.

The square root of 18861665 is about 4343.0018420443. The cubic root of 18861665 is about 266.1909844439.

The spelling of 18861665 in words is "eighteen million, eight hundred sixty-one thousand, six hundred sixty-five".