1720217 has 2 divisors, whose sum is σ = 1720218. Its totient is φ = 1720216.

The previous prime is 1720211. The next prime is 1720219. The reversal of 1720217 is 7120271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1485961 + 234256 = 1219^2 + 484^2 .

It is a cyclic number.

It is not a de Polignac number, because 1720217 - 2¹⁴ = 1703833 is a prime.

Together with 1720219, 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 (1720211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860108 + 860109.

It is an arithmetic number, because the mean of its divisors is an integer number (860109).

2^1720217 is an apocalyptic number.

It is an amenable number.

1720217 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720217 is an equidigital number, since it uses as much as digits as its factorization.

1720217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 196, while the sum is 20.

The square root of 1720217 is about 1311.5704327256. The cubic root of 1720217 is about 119.8195667978.

Adding to 1720217 its reverse (7120271), we get a palindrome (8840488).

The spelling of 1720217 in words is "one million, seven hundred twenty thousand, two hundred seventeen".