8520821 has 2 divisors, whose sum is σ = 8520822. Its totient is φ = 8520820.

The previous prime is 8520803. The next prime is 8520829. The reversal of 8520821 is 1280258.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8439025 + 81796 = 2905^2 + 286^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8520821 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8520829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4260410 + 4260411.

It is an arithmetic number, because the mean of its divisors is an integer number (4260411).

Almost surely, 2^8520821 is an apocalyptic number.

It is an amenable number.

8520821 is a deficient number, since it is larger than the sum of its proper divisors (1).

8520821 is an equidigital number, since it uses as much as digits as its factorization.

8520821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 8520821 is about 2919.0445354602. The cubic root of 8520821 is about 204.2492547915.

The spelling of 8520821 in words is "eight million, five hundred twenty thousand, eight hundred twenty-one".