216666497 has 2 divisors, whose sum is σ = 216666498. Its totient is φ = 216666496.

The previous prime is 216666493. The next prime is 216666503. The reversal of 216666497 is 794666612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 173159281 + 43507216 = 13159^2 + 6596^2 .

It is a cyclic number.

It is not a de Polignac number, because 216666497 - 2² = 216666493 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (216666493) 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, 108333248 + 108333249.

It is an arithmetic number, because the mean of its divisors is an integer number (108333249).

Almost surely, 2^216666497 is an apocalyptic number.

It is an amenable number.

216666497 is a deficient number, since it is larger than the sum of its proper divisors (1).

216666497 is an equidigital number, since it uses as much as digits as its factorization.

216666497 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 47.

The square root of 216666497 is about 14719.5956805885. The cubic root of 216666497 is about 600.6164931951.

The spelling of 216666497 in words is "two hundred sixteen million, six hundred sixty-six thousand, four hundred ninety-seven".