821441 has 2 divisors, whose sum is σ = 821442. Its totient is φ = 821440.

The previous prime is 821411. The next prime is 821449. The reversal of 821441 is 144128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 817216 + 4225 = 904^2 + 65^2 .

It is a cyclic number.

It is not a de Polignac number, because 821441 - 2⁶ = 821377 is a prime.

It is equal to p₆₅₅₂₂ and since 821441 and 65522 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (821449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410720 + 410721.

It is an arithmetic number, because the mean of its divisors is an integer number (410721).

2⁸²¹⁴⁴¹ is an apocalyptic number.

It is an amenable number.

821441 is a deficient number, since it is larger than the sum of its proper divisors (1).

821441 is an equidigital number, since it uses as much as digits as its factorization.

821441 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 256, while the sum is 20.

The square root of 821441 is about 906.3338237096. Note that the first 3 decimals coincide. The cubic root of 821441 is about 93.6538118626.

Adding to 821441 its reverse (144128), we get a palindrome (965569).

The spelling of 821441 in words is "eight hundred twenty-one thousand, four hundred forty-one".