18717665 has 4 divisors (see below), whose sum is σ = 22461204. Its totient is φ = 14974128.

The previous prime is 18717661. The next prime is 18717683. The reversal of 18717665 is 56671781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56671781 = 1621 ⋅34961.

It can be written as a sum of positive squares in 2 ways, for example, as 12759184 + 5958481 = 3572^2 + 2441^2 .

It is a cyclic number.

It is not a de Polignac number, because 18717665 - 2² = 18717661 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18717661) 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, 1871762 + ... + 1871771.

It is an arithmetic number, because the mean of its divisors is an integer number (5615301).

Almost surely, 2^18717665 is an apocalyptic number.

It is an amenable number.

18717665 is a deficient number, since it is larger than the sum of its proper divisors (3743539).

18717665 is an equidigital number, since it uses as much as digits as its factorization.

18717665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3743538.

The product of its digits is 70560, while the sum is 41.

The square root of 18717665 is about 4326.3916836089. The cubic root of 18717665 is about 265.5118385799.

The spelling of 18717665 in words is "eighteen million, seven hundred seventeen thousand, six hundred sixty-five".