217279849 has 2 divisors, whose sum is σ = 217279850. Its totient is φ = 217279848.

The previous prime is 217279847. The next prime is 217279889. The reversal of 217279849 is 948972712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 210685225 + 6594624 = 14515^2 + 2568^2 .

It is a cyclic number.

It is not a de Polignac number, because 217279849 - 2¹ = 217279847 is a prime.

Together with 217279847, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (217279841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108639924 + 108639925.

It is an arithmetic number, because the mean of its divisors is an integer number (108639925).

Almost surely, 2^217279849 is an apocalyptic number.

It is an amenable number.

217279849 is a deficient number, since it is larger than the sum of its proper divisors (1).

217279849 is an equidigital number, since it uses as much as digits as its factorization.

217279849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 508032, while the sum is 49.

The square root of 217279849 is about 14740.4154961792. The cubic root of 217279849 is about 601.1827124905.

The spelling of 217279849 in words is "two hundred seventeen million, two hundred seventy-nine thousand, eight hundred forty-nine".