1278323791 has 2 divisors, whose sum is σ = 1278323792. Its totient is φ = 1278323790.

The previous prime is 1278323779. The next prime is 1278323797. The reversal of 1278323791 is 1973238721.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1278323791 - 2⁵ = 1278323759 is a prime.

It is a super-2 number, since 2×1278323791² = 3268223429273223362, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1278323797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639161895 + 639161896.

It is an arithmetic number, because the mean of its divisors is an integer number (639161896).

Almost surely, 2^1278323791 is an apocalyptic number.

1278323791 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278323791 is an equidigital number, since it uses as much as digits as its factorization.

1278323791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127008, while the sum is 43.

The square root of 1278323791 is about 35753.6542328193. The cubic root of 1278323791 is about 1085.2928884309.

The spelling of 1278323791 in words is "one billion, two hundred seventy-eight million, three hundred twenty-three thousand, seven hundred ninety-one".