1278765197 has 2 divisors, whose sum is σ = 1278765198. Its totient is φ = 1278765196.

The previous prime is 1278765139. The next prime is 1278765199. The reversal of 1278765197 is 7915678721.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 819905956 + 458859241 = 28634^2 + 21421^2 .

It is an emirp because it is prime and its reverse (7915678721) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1278765197 - 2⁶ = 1278765133 is a prime.

Together with 1278765199, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1278765199) 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, 639382598 + 639382599.

It is an arithmetic number, because the mean of its divisors is an integer number (639382599).

Almost surely, 2^1278765197 is an apocalyptic number.

It is an amenable number.

1278765197 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278765197 is an equidigital number, since it uses as much as digits as its factorization.

1278765197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1481760, while the sum is 53.

The square root of 1278765197 is about 35759.8265795571. The cubic root of 1278765197 is about 1085.4177914921.

The spelling of 1278765197 in words is "one billion, two hundred seventy-eight million, seven hundred sixty-five thousand, one hundred ninety-seven".