27768728261 has 2 divisors, whose sum is σ = 27768728262. Its totient is φ = 27768728260.

The previous prime is 27768728227. The next prime is 27768728263. The reversal of 27768728261 is 16282786772.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19570331236 + 8198397025 = 139894^2 + 90545^2 .

It is a cyclic number.

It is not a de Polignac number, because 27768728261 - 2²² = 27764533957 is a prime.

It is a super-2 number, since 2×27768728261² (a number of 22 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 27768728263, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 27768728197 and 27768728206.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27768728263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13884364130 + 13884364131.

It is an arithmetic number, because the mean of its divisors is an integer number (13884364131).

Almost surely, 2^27768728261 is an apocalyptic number.

It is an amenable number.

27768728261 is a deficient number, since it is larger than the sum of its proper divisors (1).

27768728261 is an equidigital number, since it uses as much as digits as its factorization.

27768728261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6322176, while the sum is 56.

The spelling of 27768728261 in words is "twenty-seven billion, seven hundred sixty-eight million, seven hundred twenty-eight thousand, two hundred sixty-one".