77765813 has 2 divisors, whose sum is σ = 77765814. Its totient is φ = 77765812.

The previous prime is 77765767. The next prime is 77765827. The reversal of 77765813 is 31856777.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60109009 + 17656804 = 7753^2 + 4202^2 .

It is a cyclic number.

It is not a de Polignac number, because 77765813 - 2⁸ = 77765557 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77765843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38882906 + 38882907.

It is an arithmetic number, because the mean of its divisors is an integer number (38882907).

Almost surely, 2^77765813 is an apocalyptic number.

It is an amenable number.

77765813 is a deficient number, since it is larger than the sum of its proper divisors (1).

77765813 is an equidigital number, since it uses as much as digits as its factorization.

77765813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 246960, while the sum is 44.

The square root of 77765813 is about 8818.4926716531. The cubic root of 77765813 is about 426.8378321898.

The spelling of 77765813 in words is "seventy-seven million, seven hundred sixty-five thousand, eight hundred thirteen".