77721906563177 has 2 divisors, whose sum is σ = 77721906563178. Its totient is φ = 77721906563176.

The previous prime is 77721906563089. The next prime is 77721906563179. The reversal of 77721906563177 is 77136560912777.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63099764183296 + 14622142379881 = 7943536^2 + 3823891^2 .

It is a cyclic number.

It is not a de Polignac number, because 77721906563177 - 2³² = 77717611595881 is a prime.

Together with 77721906563179, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (77721906563179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38860953281588 + 38860953281589.

It is an arithmetic number, because the mean of its divisors is an integer number (38860953281589).

Almost surely, 2^{77721906563177} is an apocalyptic number.

It is an amenable number.

77721906563177 is a deficient number, since it is larger than the sum of its proper divisors (1).

77721906563177 is an equidigital number, since it uses as much as digits as its factorization.

77721906563177 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 163364040, while the sum is 68.

The spelling of 77721906563177 in words is "seventy-seven trillion, seven hundred twenty-one billion, nine hundred six million, five hundred sixty-three thousand, one hundred seventy-seven".