77681641 has 2 divisors, whose sum is σ = 77681642. Its totient is φ = 77681640.

The previous prime is 77681579. The next prime is 77681651. The reversal of 77681641 is 14618677.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60217600 + 17464041 = 7760^2 + 4179^2 .

It is an emirp because it is prime and its reverse (14618677) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77681641 - 2⁹ = 77681129 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 77681594 and 77681603.

It is not a weakly prime, because it can be changed into another prime (77681651) 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, 38840820 + 38840821.

It is an arithmetic number, because the mean of its divisors is an integer number (38840821).

Almost surely, 2^77681641 is an apocalyptic number.

It is an amenable number.

77681641 is a deficient number, since it is larger than the sum of its proper divisors (1).

77681641 is an equidigital number, since it uses as much as digits as its factorization.

77681641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 40.

The square root of 77681641 is about 8813.7189086106. The cubic root of 77681641 is about 426.6837766440.

It can be divided in two parts, 7768 and 1641, that added together give a square (9409 = 97²).

The spelling of 77681641 in words is "seventy-seven million, six hundred eighty-one thousand, six hundred forty-one".