39988966651721 has 2 divisors, whose sum is σ = 39988966651722. Its totient is φ = 39988966651720.

The previous prime is 39988966651703. The next prime is 39988966651807. The reversal of 39988966651721 is 12715666988993.

39988966651721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27380217877321 + 12608748774400 = 5232611^2 + 3550880^2 .

It is an emirp because it is prime and its reverse (12715666988993) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-39988966651721 is a prime.

It is not a weakly prime, because it can be changed into another prime (39988966651421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19994483325860 + 19994483325861.

It is an arithmetic number, because the mean of its divisors is an integer number (19994483325861).

Almost surely, 2^{39988966651721} is an apocalyptic number.

It is an amenable number.

39988966651721 is a deficient number, since it is larger than the sum of its proper divisors (1).

39988966651721 is an equidigital number, since it uses as much as digits as its factorization.

39988966651721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2116316160, while the sum is 80.

The spelling of 39988966651721 in words is "thirty-nine trillion, nine hundred eighty-eight billion, nine hundred sixty-six million, six hundred fifty-one thousand, seven hundred twenty-one".