16520813 has 4 divisors (see below), whose sum is σ = 16791708. Its totient is φ = 16249920.

The previous prime is 16520797. The next prime is 16520837. The reversal of 16520813 is 31802561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6165289 + 10355524 = 2483^2 + 3218^2 .

It is a cyclic number.

It is not a de Polignac number, because 16520813 - 2⁴ = 16520797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16520893) 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, 135356 + ... + 135477.

It is an arithmetic number, because the mean of its divisors is an integer number (4197927).

Almost surely, 2^16520813 is an apocalyptic number.

It is an amenable number.

16520813 is a deficient number, since it is larger than the sum of its proper divisors (270895).

16520813 is an equidigital number, since it uses as much as digits as its factorization.

16520813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270894.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 16520813 is about 4064.5802981366. The cubic root of 16520813 is about 254.6891663082.

The spelling of 16520813 in words is "sixteen million, five hundred twenty thousand, eight hundred thirteen".