216666641 has 2 divisors, whose sum is σ = 216666642. Its totient is φ = 216666640.

The previous prime is 216666631. The next prime is 216666643. The reversal of 216666641 is 146666612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 215502400 + 1164241 = 14680^2 + 1079^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216666641 is a prime.

Together with 216666643, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 216666595 and 216666604.

It is not a weakly prime, because it can be changed into another prime (216666643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108333320 + 108333321.

It is an arithmetic number, because the mean of its divisors is an integer number (108333321).

Almost surely, 2^216666641 is an apocalyptic number.

It is an amenable number.

216666641 is a deficient number, since it is larger than the sum of its proper divisors (1).

216666641 is an equidigital number, since it uses as much as digits as its factorization.

216666641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 38.

The square root of 216666641 is about 14719.6005720264. The cubic root of 216666641 is about 600.6166262549.

The spelling of 216666641 in words is "two hundred sixteen million, six hundred sixty-six thousand, six hundred forty-one".