1278716779 has 2 divisors, whose sum is σ = 1278716780. Its totient is φ = 1278716778.

The previous prime is 1278716771. The next prime is 1278716821. The reversal of 1278716779 is 9776178721.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1278716779 - 2³ = 1278716771 is a prime.

It is a super-2 number, since 2×1278716779² = 3270233201792269682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1278716771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639358389 + 639358390.

It is an arithmetic number, because the mean of its divisors is an integer number (639358390).

Almost surely, 2^1278716779 is an apocalyptic number.

1278716779 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278716779 is an equidigital number, since it uses as much as digits as its factorization.

1278716779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2074464, while the sum is 55.

The square root of 1278716779 is about 35759.1495844071. The cubic root of 1278716779 is about 1085.4040922291.

The spelling of 1278716779 in words is "one billion, two hundred seventy-eight million, seven hundred sixteen thousand, seven hundred seventy-nine".