9780689521 has 2 divisors, whose sum is σ = 9780689522. Its totient is φ = 9780689520.

The previous prime is 9780689453. The next prime is 9780689531. The reversal of 9780689521 is 1259860879.

9780689521 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8983248400 + 797441121 = 94780^2 + 28239^2 .

It is an emirp because it is prime and its reverse (1259860879) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9780689521 - 2²⁹ = 9243818609 is a prime.

It is not a weakly prime, because it can be changed into another prime (9780689531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890344760 + 4890344761.

It is an arithmetic number, because the mean of its divisors is an integer number (4890344761).

Almost surely, 2^9780689521 is an apocalyptic number.

It is an amenable number.

9780689521 is a deficient number, since it is larger than the sum of its proper divisors (1).

9780689521 is an equidigital number, since it uses as much as digits as its factorization.

9780689521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2177280, while the sum is 55.

The square root of 9780689521 is about 98897.3686252572. The cubic root of 9780689521 is about 2138.5684606659.

The spelling of 9780689521 in words is "nine billion, seven hundred eighty million, six hundred eighty-nine thousand, five hundred twenty-one".