1278291787 has 2 divisors, whose sum is σ = 1278291788. Its totient is φ = 1278291786.

The previous prime is 1278291779. The next prime is 1278291797. The reversal of 1278291787 is 7871928721.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1278291787 - 2³ = 1278291779 is a prime.

It is not a weakly prime, because it can be changed into another prime (1278291797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639145893 + 639145894.

It is an arithmetic number, because the mean of its divisors is an integer number (639145894).

Almost surely, 2^1278291787 is an apocalyptic number.

1278291787 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278291787 is an equidigital number, since it uses as much as digits as its factorization.

1278291787 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 790272, while the sum is 52.

The square root of 1278291787 is about 35753.2066673746. The cubic root of 1278291787 is about 1085.2838312568.

The spelling of 1278291787 in words is "one billion, two hundred seventy-eight million, two hundred ninety-one thousand, seven hundred eighty-seven".