78778281557 has 2 divisors, whose sum is σ = 78778281558. Its totient is φ = 78778281556.

The previous prime is 78778281521. The next prime is 78778281587. The reversal of 78778281557 is 75518287787.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69646376836 + 9131904721 = 263906^2 + 95561^2 .

It is a cyclic number.

It is not a de Polignac number, because 78778281557 - 2¹⁰ = 78778280533 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 78778281493 and 78778281502.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78778281587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39389140778 + 39389140779.

It is an arithmetic number, because the mean of its divisors is an integer number (39389140779).

Almost surely, 2^78778281557 is an apocalyptic number.

It is an amenable number.

78778281557 is a deficient number, since it is larger than the sum of its proper divisors (1).

78778281557 is an equidigital number, since it uses as much as digits as its factorization.

78778281557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 61465600, while the sum is 65.

The spelling of 78778281557 in words is "seventy-eight billion, seven hundred seventy-eight million, two hundred eighty-one thousand, five hundred fifty-seven".