7725666521 has 2 divisors, whose sum is σ = 7725666522. Its totient is φ = 7725666520.

The previous prime is 7725666517. The next prime is 7725666527. The reversal of 7725666521 is 1256665277.

7725666521 is digitally balanced in base 3, 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., 3910751296 + 3814915225 = 62536^2 + 61765^2 .

It is a cyclic number.

It is not a de Polignac number, because 7725666521 - 2² = 7725666517 is a prime.

It is not a weakly prime, because it can be changed into another prime (7725666527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3862833260 + 3862833261.

It is an arithmetic number, because the mean of its divisors is an integer number (3862833261).

Almost surely, 2^7725666521 is an apocalyptic number.

It is an amenable number.

7725666521 is a deficient number, since it is larger than the sum of its proper divisors (1).

7725666521 is an equidigital number, since it uses as much as digits as its factorization.

7725666521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1058400, while the sum is 47.

The square root of 7725666521 is about 87895.7707799414. The cubic root of 7725666521 is about 1976.8724662173.

The spelling of 7725666521 in words is "seven billion, seven hundred twenty-five million, six hundred sixty-six thousand, five hundred twenty-one".