78821077 has 2 divisors, whose sum is σ = 78821078. Its totient is φ = 78821076.

The previous prime is 78821053. The next prime is 78821117. The reversal of 78821077 is 77012887.

It is a happy number.

It is an a-pointer prime, because the next prime (78821117) can be obtained adding 78821077 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62869041 + 15952036 = 7929^2 + 3994^2 .

It is a cyclic number.

It is not a de Polignac number, because 78821077 - 2¹¹ = 78819029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78821047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39410538 + 39410539.

It is an arithmetic number, because the mean of its divisors is an integer number (39410539).

Almost surely, 2^78821077 is an apocalyptic number.

It is an amenable number.

78821077 is a deficient number, since it is larger than the sum of its proper divisors (1).

78821077 is an equidigital number, since it uses as much as digits as its factorization.

78821077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43904, while the sum is 40.

The square root of 78821077 is about 8878.1235066877. The cubic root of 78821077 is about 428.7598611122.

The spelling of 78821077 in words is "seventy-eight million, eight hundred twenty-one thousand, seventy-seven".