216505613 has 2 divisors, whose sum is σ = 216505614. Its totient is φ = 216505612.

The previous prime is 216505607. The next prime is 216505631. The reversal of 216505613 is 316505612.

Together with next prime (216505631) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216295849 + 209764 = 14707^2 + 458^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216505613 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216505603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108252806 + 108252807.

It is an arithmetic number, because the mean of its divisors is an integer number (108252807).

Almost surely, 2^216505613 is an apocalyptic number.

It is an amenable number.

216505613 is a deficient number, since it is larger than the sum of its proper divisors (1).

216505613 is an equidigital number, since it uses as much as digits as its factorization.

216505613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5400, while the sum is 29.

The square root of 216505613 is about 14714.1297058304. The cubic root of 216505613 is about 600.4677953696.

Subtracting 216505613 from its reverse (316505612), we obtain a palindrome (99999999).

The spelling of 216505613 in words is "two hundred sixteen million, five hundred five thousand, six hundred thirteen".