78942217 has 2 divisors, whose sum is σ = 78942218. Its totient is φ = 78942216.

The previous prime is 78942191. The next prime is 78942221. The reversal of 78942217 is 71224987.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76807696 + 2134521 = 8764^2 + 1461^2 .

It is an emirp because it is prime and its reverse (71224987) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78942217 - 2¹⁵ = 78909449 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78942217.

It is not a weakly prime, because it can be changed into another prime (78942257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39471108 + 39471109.

It is an arithmetic number, because the mean of its divisors is an integer number (39471109).

Almost surely, 2^78942217 is an apocalyptic number.

It is an amenable number.

78942217 is a deficient number, since it is larger than the sum of its proper divisors (1).

78942217 is an equidigital number, since it uses as much as digits as its factorization.

78942217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 40.

The square root of 78942217 is about 8884.9432750018. The cubic root of 78942217 is about 428.9794021513.

The spelling of 78942217 in words is "seventy-eight million, nine hundred forty-two thousand, two hundred seventeen".