2779278064561 has 2 divisors, whose sum is σ = 2779278064562. Its totient is φ = 2779278064560.

The previous prime is 2779278064559. The next prime is 2779278064567. The reversal of 2779278064561 is 1654608729772.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1447885164961 + 1331392899600 = 1203281^2 + 1153860^2 .

It is a cyclic number.

It is not a de Polignac number, because 2779278064561 - 2¹ = 2779278064559 is a prime.

Together with 2779278064559, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 2779278064493 and 2779278064502.

It is not a weakly prime, because it can be changed into another prime (2779278064567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1389639032280 + 1389639032281.

It is an arithmetic number, because the mean of its divisors is an integer number (1389639032281).

Almost surely, 2^{2779278064561} is an apocalyptic number.

It is an amenable number.

2779278064561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2779278064561 is an equidigital number, since it uses as much as digits as its factorization.

2779278064561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 71124480, while the sum is 64.

The spelling of 2779278064561 in words is "two trillion, seven hundred seventy-nine billion, two hundred seventy-eight million, sixty-four thousand, five hundred sixty-one".