77653439021 has 2 divisors, whose sum is σ = 77653439022. Its totient is φ = 77653439020.

The previous prime is 77653439009. The next prime is 77653439029. The reversal of 77653439021 is 12093435677.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74575963396 + 3077475625 = 273086^2 + 55475^2 .

It is an emirp because it is prime and its reverse (12093435677) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77653439021 - 2³⁰ = 76579697197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77653439029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38826719510 + 38826719511.

It is an arithmetic number, because the mean of its divisors is an integer number (38826719511).

Almost surely, 2^77653439021 is an apocalyptic number.

It is an amenable number.

77653439021 is a deficient number, since it is larger than the sum of its proper divisors (1).

77653439021 is an equidigital number, since it uses as much as digits as its factorization.

77653439021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 952560, while the sum is 47.

The spelling of 77653439021 in words is "seventy-seven billion, six hundred fifty-three million, four hundred thirty-nine thousand, twenty-one".