278618855336561 has 2 divisors, whose sum is σ = 278618855336562. Its totient is φ = 278618855336560.

The previous prime is 278618855336543. The next prime is 278618855336573. The reversal of 278618855336561 is 165633558816872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 238564829455936 + 40054025880625 = 15445544^2 + 6328825^2 .

It is a cyclic number.

It is not a de Polignac number, because 278618855336561 - 2¹⁰ = 278618855335537 is a prime.

It is not a weakly prime, because it can be changed into another prime (278618855336531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139309427668280 + 139309427668281.

It is an arithmetic number, because the mean of its divisors is an integer number (139309427668281).

Almost surely, 2^{278618855336561} is an apocalyptic number.

It is an amenable number.

278618855336561 is a deficient number, since it is larger than the sum of its proper divisors (1).

278618855336561 is an equidigital number, since it uses as much as digits as its factorization.

278618855336561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1741824000, while the sum is 74.

The spelling of 278618855336561 in words is "two hundred seventy-eight trillion, six hundred eighteen billion, eight hundred fifty-five million, three hundred thirty-six thousand, five hundred sixty-one".