816873521 has 2 divisors, whose sum is σ = 816873522. Its totient is φ = 816873520.

The previous prime is 816873503. The next prime is 816873527. The reversal of 816873521 is 125378618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 816816400 + 57121 = 28580^2 + 239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-816873521 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (816873527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408436760 + 408436761.

It is an arithmetic number, because the mean of its divisors is an integer number (408436761).

Almost surely, 2^816873521 is an apocalyptic number.

It is an amenable number.

816873521 is a deficient number, since it is larger than the sum of its proper divisors (1).

816873521 is an equidigital number, since it uses as much as digits as its factorization.

816873521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 80640, while the sum is 41.

The square root of 816873521 is about 28580.9993002344. Note that the first 3 decimals coincide. The cubic root of 816873521 is about 934.7990726130.

The spelling of 816873521 in words is "eight hundred sixteen million, eight hundred seventy-three thousand, five hundred twenty-one".