840246217 has 2 divisors, whose sum is σ = 840246218. Its totient is φ = 840246216.

The previous prime is 840246179. The next prime is 840246221. The reversal of 840246217 is 712642048.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 792760336 + 47485881 = 28156^2 + 6891^2 .

It is a cyclic number.

It is not a de Polignac number, because 840246217 - 2¹⁵ = 840213449 is a prime.

It is a super-2 number, since 2×840246217² = 1412027410365622178, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (840246247) 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, 420123108 + 420123109.

It is an arithmetic number, because the mean of its divisors is an integer number (420123109).

Almost surely, 2^840246217 is an apocalyptic number.

It is an amenable number.

840246217 is a deficient number, since it is larger than the sum of its proper divisors (1).

840246217 is an equidigital number, since it uses as much as digits as its factorization.

840246217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21504, while the sum is 34.

The square root of 840246217 is about 28987.0008279573. Note that the first 3 decimals coincide. The cubic root of 840246217 is about 943.6309756653.

The spelling of 840246217 in words is "eight hundred forty million, two hundred forty-six thousand, two hundred seventeen".