216666643 has 2 divisors, whose sum is σ = 216666644. Its totient is φ = 216666642.

The previous prime is 216666641. The next prime is 216666661. The reversal of 216666643 is 346666612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216666643 - 2¹ = 216666641 is a prime.

Together with 216666641, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 216666596 and 216666605.

It is not a weakly prime, because it can be changed into another prime (216666641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108333321 + 108333322.

It is an arithmetic number, because the mean of its divisors is an integer number (108333322).

Almost surely, 2^216666643 is an apocalyptic number.

216666643 is a deficient number, since it is larger than the sum of its proper divisors (1).

216666643 is an equidigital number, since it uses as much as digits as its factorization.

216666643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 40.

The square root of 216666643 is about 14719.6006399630. The cubic root of 216666643 is about 600.6166281029.

The spelling of 216666643 in words is "two hundred sixteen million, six hundred sixty-six thousand, six hundred forty-three".