1278229391 has 2 divisors, whose sum is σ = 1278229392. Its totient is φ = 1278229390.

The previous prime is 1278229369. The next prime is 1278229399. The reversal of 1278229391 is 1939228721.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1278229391 - 2⁶ = 1278229327 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1278229399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639114695 + 639114696.

It is an arithmetic number, because the mean of its divisors is an integer number (639114696).

Almost surely, 2^1278229391 is an apocalyptic number.

1278229391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278229391 is an equidigital number, since it uses as much as digits as its factorization.

1278229391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 44.

The square root of 1278229391 is about 35752.3340636664. The cubic root of 1278229391 is about 1085.2661726720.

The spelling of 1278229391 in words is "one billion, two hundred seventy-eight million, two hundred twenty-nine thousand, three hundred ninety-one".