216506565 has 24 divisors (see below), whose sum is σ = 409395168. Its totient is φ = 104972640.

The previous prime is 216506561. The next prime is 216506593. The reversal of 216506565 is 565605612.

It is a happy number.

216506565 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 216506565 - 2² = 216506561 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216506561) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 218199 + ... + 219188.

It is an arithmetic number, because the mean of its divisors is an integer number (17058132).

Almost surely, 2^216506565 is an apocalyptic number.

It is an amenable number.

216506565 is a deficient number, since it is larger than the sum of its proper divisors (192888603).

216506565 is a wasteful number, since it uses less digits than its factorization.

216506565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 437409 (or 437406 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The square root of 216506565 is about 14714.1620556524. The cubic root of 216506565 is about 600.4686754768.

The spelling of 216506565 in words is "two hundred sixteen million, five hundred six thousand, five hundred sixty-five".