18709 has 4 divisors (see below), whose sum is σ = 19116. Its totient is φ = 18304.

The previous prime is 18701. The next prime is 18713. The reversal of 18709 is 90781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90781 = 23 ⋅3947.

It can be written as a sum of positive squares in 2 ways, for example, as 10609 + 8100 = 103^2 + 90^2 .

It is a cyclic number.

It is not a de Polignac number, because 18709 - 2³ = 18701 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18701) 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, 124 + ... + 229.

It is an arithmetic number, because the mean of its divisors is an integer number (4779).

2¹⁸⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

18709 is a deficient number, since it is larger than the sum of its proper divisors (407).

18709 is an equidigital number, since it uses as much as digits as its factorization.

18709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406.

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 18709 is about 136.7808466124. The cubic root of 18709 is about 26.5470860976.

It can be divided in two parts, 18 and 709, that added together give a palindrome (727).

The spelling of 18709 in words is "eighteen thousand, seven hundred nine".