77451645728621 has 2 divisors, whose sum is σ = 77451645728622. Its totient is φ = 77451645728620.

The previous prime is 77451645728603. The next prime is 77451645728657. The reversal of 77451645728621 is 12682754615477.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57498325045225 + 19953320683396 = 7582765^2 + 4466914^2 .

It is an emirp because it is prime and its reverse (12682754615477) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77451645728621 - 2²⁶ = 77451578619757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77451645718621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38725822864310 + 38725822864311.

It is an arithmetic number, because the mean of its divisors is an integer number (38725822864311).

Almost surely, 2^{77451645728621} is an apocalyptic number.

It is an amenable number.

77451645728621 is a deficient number, since it is larger than the sum of its proper divisors (1).

77451645728621 is an equidigital number, since it uses as much as digits as its factorization.

77451645728621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 158054400, while the sum is 65.

The spelling of 77451645728621 in words is "seventy-seven trillion, four hundred fifty-one billion, six hundred forty-five million, seven hundred twenty-eight thousand, six hundred twenty-one".