7821329521 has 2 divisors, whose sum is σ = 7821329522. Its totient is φ = 7821329520.

The previous prime is 7821329507. The next prime is 7821329533. The reversal of 7821329521 is 1259231287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7015905121 + 805424400 = 83761^2 + 28380^2 .

It is an emirp because it is prime and its reverse (1259231287) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7821329521 - 2⁵ = 7821329489 is a prime.

It is a super-2 number, since 2×7821329521² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7821329591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3910664760 + 3910664761.

It is an arithmetic number, because the mean of its divisors is an integer number (3910664761).

Almost surely, 2^7821329521 is an apocalyptic number.

It is an amenable number.

7821329521 is a deficient number, since it is larger than the sum of its proper divisors (1).

7821329521 is an equidigital number, since it uses as much as digits as its factorization.

7821329521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 40.

The square root of 7821329521 is about 88438.2808573301. The cubic root of 7821329521 is about 1984.9985530427.

The spelling of 7821329521 in words is "seven billion, eight hundred twenty-one million, three hundred twenty-nine thousand, five hundred twenty-one".