77019820561 has 2 divisors, whose sum is σ = 77019820562. Its totient is φ = 77019820560.

The previous prime is 77019820529. The next prime is 77019820597. The reversal of 77019820561 is 16502891077.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76286440000 + 733380561 = 276200^2 + 27081^2 .

It is a cyclic number.

It is not a de Polignac number, because 77019820561 - 2⁵ = 77019820529 is a prime.

It is not a weakly prime, because it can be changed into another prime (77019220561) 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, 38509910280 + 38509910281.

It is an arithmetic number, because the mean of its divisors is an integer number (38509910281).

Almost surely, 2^77019820561 is an apocalyptic number.

It is an amenable number.

77019820561 is a deficient number, since it is larger than the sum of its proper divisors (1).

77019820561 is an equidigital number, since it uses as much as digits as its factorization.

77019820561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 211680, while the sum is 46.

The spelling of 77019820561 in words is "seventy-seven billion, nineteen million, eight hundred twenty thousand, five hundred sixty-one".