18520013 has 4 divisors (see below), whose sum is σ = 18529500. Its totient is φ = 18510528.

The previous prime is 18520001. The next prime is 18520031. The reversal of 18520013 is 31002581.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5466244 + 13053769 = 2338^2 + 3613^2 .

It is a cyclic number.

It is not a de Polignac number, because 18520013 - 2⁴ = 18519997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18520043) 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, 620 + ... + 6117.

It is an arithmetic number, because the mean of its divisors is an integer number (4632375).

Almost surely, 2^18520013 is an apocalyptic number.

It is an amenable number.

18520013 is a deficient number, since it is larger than the sum of its proper divisors (9487).

18520013 is an equidigital number, since it uses as much as digits as its factorization.

18520013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9486.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 18520013 is about 4303.4884686728. The cubic root of 18520013 is about 264.5739588277.

Adding to 18520013 its reverse (31002581), we get a palindrome (49522594).

The spelling of 18520013 in words is "eighteen million, five hundred twenty thousand, thirteen".