77964785621 has 2 divisors, whose sum is σ = 77964785622. Its totient is φ = 77964785620.

The previous prime is 77964785609. The next prime is 77964785627. The reversal of 77964785621 is 12658746977.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 40648204996 + 37316580625 = 201614^2 + 193175^2 .

It is a cyclic number.

It is not a de Polignac number, because 77964785621 - 2⁶ = 77964785557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77964785627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38982392810 + 38982392811.

It is an arithmetic number, because the mean of its divisors is an integer number (38982392811).

Almost surely, 2^77964785621 is an apocalyptic number.

It is an amenable number.

77964785621 is a deficient number, since it is larger than the sum of its proper divisors (1).

77964785621 is an equidigital number, since it uses as much as digits as its factorization.

77964785621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 35562240, while the sum is 62.

The spelling of 77964785621 in words is "seventy-seven billion, nine hundred sixty-four million, seven hundred eighty-five thousand, six hundred twenty-one".