820871321 has 2 divisors, whose sum is σ = 820871322. Its totient is φ = 820871320.

The previous prime is 820871279. The next prime is 820871323. The reversal of 820871321 is 123178028.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 800041225 + 20830096 = 28285^2 + 4564^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-820871321 is a prime.

Together with 820871323, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (820871323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410435660 + 410435661.

It is an arithmetic number, because the mean of its divisors is an integer number (410435661).

Almost surely, 2^820871321 is an apocalyptic number.

It is an amenable number.

820871321 is a deficient number, since it is larger than the sum of its proper divisors (1).

820871321 is an equidigital number, since it uses as much as digits as its factorization.

820871321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 820871321 is about 28650.8520117640. The cubic root of 820871321 is about 936.3215684894.

The spelling of 820871321 in words is "eight hundred twenty million, eight hundred seventy-one thousand, three hundred twenty-one".