1278427649 has 2 divisors, whose sum is σ = 1278427650. Its totient is φ = 1278427648.

The previous prime is 1278427643. The next prime is 1278427679. The reversal of 1278427649 is 9467248721.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1221153025 + 57274624 = 34945^2 + 7568^2 .

It is a cyclic number.

It is not a de Polignac number, because 1278427649 - 2⁸ = 1278427393 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1278427597 and 1278427606.

It is not a weakly prime, because it can be changed into another prime (1278427643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639213824 + 639213825.

It is an arithmetic number, because the mean of its divisors is an integer number (639213825).

Almost surely, 2^1278427649 is an apocalyptic number.

It is an amenable number.

1278427649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278427649 is an equidigital number, since it uses as much as digits as its factorization.

1278427649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1354752, while the sum is 50.

The square root of 1278427649 is about 35755.1066143006. The cubic root of 1278427649 is about 1085.3222793403.

The spelling of 1278427649 in words is "one billion, two hundred seventy-eight million, four hundred twenty-seven thousand, six hundred forty-nine".