1278206977217 has 2 divisors, whose sum is σ = 1278206977218. Its totient is φ = 1278206977216.

The previous prime is 1278206977163. The next prime is 1278206977237. The reversal of 1278206977217 is 7127796028721.

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., 1142741758081 + 135465219136 = 1068991^2 + 368056^2 .

It is a cyclic number.

It is not a de Polignac number, because 1278206977217 - 2⁶ = 1278206977153 is a prime.

It is not a weakly prime, because it can be changed into another prime (1278206977237) 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, 639103488608 + 639103488609.

It is an arithmetic number, because the mean of its divisors is an integer number (639103488609).

Almost surely, 2^{1278206977217} is an apocalyptic number.

It is an amenable number.

1278206977217 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278206977217 is an equidigital number, since it uses as much as digits as its factorization.

1278206977217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8297856, while the sum is 59.

The spelling of 1278206977217 in words is "one trillion, two hundred seventy-eight billion, two hundred six million, nine hundred seventy-seven thousand, two hundred seventeen".