216556517 has 2 divisors, whose sum is σ = 216556518. Its totient is φ = 216556516.

The previous prime is 216556469. The next prime is 216556553. The reversal of 216556517 is 715655612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 187115041 + 29441476 = 13679^2 + 5426^2 .

It is a cyclic number.

It is not a de Polignac number, because 216556517 - 2¹² = 216552421 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 (216556577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108278258 + 108278259.

It is an arithmetic number, because the mean of its divisors is an integer number (108278259).

Almost surely, 2^216556517 is an apocalyptic number.

It is an amenable number.

216556517 is a deficient number, since it is larger than the sum of its proper divisors (1).

216556517 is an equidigital number, since it uses as much as digits as its factorization.

216556517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63000, while the sum is 38.

The square root of 216556517 is about 14715.8593700810. The cubic root of 216556517 is about 600.5148516052.

The spelling of 216556517 in words is "two hundred sixteen million, five hundred fifty-six thousand, five hundred seventeen".