68721519509 has 2 divisors, whose sum is σ = 68721519510. Its totient is φ = 68721519508.

The previous prime is 68721519497. The next prime is 68721519523. The reversal of 68721519509 is 90591512786.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44392383025 + 24329136484 = 210695^2 + 155978^2 .

It is a cyclic number.

It is not a de Polignac number, because 68721519509 - 2¹² = 68721515413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68721519569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34360759754 + 34360759755.

It is an arithmetic number, because the mean of its divisors is an integer number (34360759755).

Almost surely, 2^68721519509 is an apocalyptic number.

It is an amenable number.

68721519509 is a deficient number, since it is larger than the sum of its proper divisors (1).

68721519509 is an equidigital number, since it uses as much as digits as its factorization.

68721519509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1360800, while the sum is 53.

The spelling of 68721519509 in words is "sixty-eight billion, seven hundred twenty-one million, five hundred nineteen thousand, five hundred nine".