216623917 has 2 divisors, whose sum is σ = 216623918. Its totient is φ = 216623916.

The previous prime is 216623861. The next prime is 216623933. The reversal of 216623917 is 719326612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 115541001 + 101082916 = 10749^2 + 10054^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216623917 is a prime.

It is a Chen prime.

It is equal to p_11946862 and since 216623917 and 11946862 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216623117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108311958 + 108311959.

It is an arithmetic number, because the mean of its divisors is an integer number (108311959).

Almost surely, 2^216623917 is an apocalyptic number.

It is an amenable number.

216623917 is a deficient number, since it is larger than the sum of its proper divisors (1).

216623917 is an equidigital number, since it uses as much as digits as its factorization.

216623917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 37.

The square root of 216623917 is about 14718.1492382704. The cubic root of 216623917 is about 600.5771455862.

The spelling of 216623917 in words is "two hundred sixteen million, six hundred twenty-three thousand, nine hundred seventeen".