18684613 has 4 divisors (see below), whose sum is σ = 19328940. Its totient is φ = 18040288.

The previous prime is 18684587. The next prime is 18684647. The reversal of 18684613 is 31648681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31648681 = 337 ⋅93913.

It can be written as a sum of positive squares in 2 ways, for example, as 5846724 + 12837889 = 2418^2 + 3583^2 .

It is a cyclic number.

It is not a de Polignac number, because 18684613 - 2⁹ = 18684101 is a prime.

It is a super-2 number, since 2×18684613² = 698229525919538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18684013) 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, 322120 + ... + 322177.

It is an arithmetic number, because the mean of its divisors is an integer number (4832235).

Almost surely, 2^18684613 is an apocalyptic number.

It is an amenable number.

18684613 is a deficient number, since it is larger than the sum of its proper divisors (644327).

18684613 is an equidigital number, since it uses as much as digits as its factorization.

18684613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644326.

The product of its digits is 27648, while the sum is 37.

The square root of 18684613 is about 4322.5701845083. The cubic root of 18684613 is about 265.3554645914.

The spelling of 18684613 in words is "eighteen million, six hundred eighty-four thousand, six hundred thirteen".