216566513 has 4 divisors (see below), whose sum is σ = 222419700. Its totient is φ = 210713328.

The previous prime is 216566507. The next prime is 216566557. The reversal of 216566513 is 315665612.

216566513 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 145130209 + 71436304 = 12047^2 + 8452^2 .

It is a cyclic number.

It is not a de Polignac number, because 216566513 - 2⁸ = 216566257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (216566593) 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, 2926538 + ... + 2926611.

It is an arithmetic number, because the mean of its divisors is an integer number (55604925).

Almost surely, 2^216566513 is an apocalyptic number.

It is an amenable number.

216566513 is a deficient number, since it is larger than the sum of its proper divisors (5853187).

216566513 is an equidigital number, since it uses as much as digits as its factorization.

216566513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5853186.

The product of its digits is 32400, while the sum is 35.

The square root of 216566513 is about 14716.1989997417. The cubic root of 216566513 is about 600.5240911549.

Subtracting 216566513 from its reverse (315665612), we obtain a palindrome (99099099).

The spelling of 216566513 in words is "two hundred sixteen million, five hundred sixty-six thousand, five hundred thirteen".