77928413561 has 2 divisors, whose sum is σ = 77928413562. Its totient is φ = 77928413560.

The previous prime is 77928413513. The next prime is 77928413587. The reversal of 77928413561 is 16531482977.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72622165225 + 5306248336 = 269485^2 + 72844^2 .

It is an emirp because it is prime and its reverse (16531482977) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77928413561 - 2¹⁴ = 77928397177 is a prime.

It is not a weakly prime, because it can be changed into another prime (77928413161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38964206780 + 38964206781.

It is an arithmetic number, because the mean of its divisors is an integer number (38964206781).

Almost surely, 2^77928413561 is an apocalyptic number.

It is an amenable number.

77928413561 is a deficient number, since it is larger than the sum of its proper divisors (1).

77928413561 is an equidigital number, since it uses as much as digits as its factorization.

77928413561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2540160, while the sum is 53.

The spelling of 77928413561 in words is "seventy-seven billion, nine hundred twenty-eight million, four hundred thirteen thousand, five hundred sixty-one".