77069815721 has 2 divisors, whose sum is σ = 77069815722. Its totient is φ = 77069815720.

The previous prime is 77069815709. The next prime is 77069815777. The reversal of 77069815721 is 12751896077.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55136205721 + 21933610000 = 234811^2 + 148100^2 .

It is an emirp because it is prime and its reverse (12751896077) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77069815721 - 2²² = 77065621417 is a prime.

It is not a weakly prime, because it can be changed into another prime (77069815021) 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, 38534907860 + 38534907861.

It is an arithmetic number, because the mean of its divisors is an integer number (38534907861).

Almost surely, 2^77069815721 is an apocalyptic number.

It is an amenable number.

77069815721 is a deficient number, since it is larger than the sum of its proper divisors (1).

77069815721 is an equidigital number, since it uses as much as digits as its factorization.

77069815721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1481760, while the sum is 53.

The spelling of 77069815721 in words is "seventy-seven billion, sixty-nine million, eight hundred fifteen thousand, seven hundred twenty-one".