216617909 has 2 divisors, whose sum is σ = 216617910. Its totient is φ = 216617908.

The previous prime is 216617881. The next prime is 216617911. The reversal of 216617909 is 909716612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 206726884 + 9891025 = 14378^2 + 3145^2 .

It is a cyclic number.

It is not a de Polignac number, because 216617909 - 2¹⁶ = 216552373 is a prime.

Together with 216617911, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216617939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108308954 + 108308955.

It is an arithmetic number, because the mean of its divisors is an integer number (108308955).

Almost surely, 2^216617909 is an apocalyptic number.

It is an amenable number.

216617909 is a deficient number, since it is larger than the sum of its proper divisors (1).

216617909 is an equidigital number, since it uses as much as digits as its factorization.

216617909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 216617909 is about 14717.9451351063. The cubic root of 216617909 is about 600.5715932586.

The spelling of 216617909 in words is "two hundred sixteen million, six hundred seventeen thousand, nine hundred nine".