821801 has 2 divisors, whose sum is σ = 821802. Its totient is φ = 821800.

The previous prime is 821771. The next prime is 821803. The reversal of 821801 is 108128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 811801 + 10000 = 901^2 + 100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821801 is a prime.

Together with 821803, it forms a pair of twin primes.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 821801.

It is not a weakly prime, because it can be changed into another prime (821803) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410900 + 410901.

It is an arithmetic number, because the mean of its divisors is an integer number (410901).

2⁸²¹⁸⁰¹ is an apocalyptic number.

It is an amenable number.

821801 is a deficient number, since it is larger than the sum of its proper divisors (1).

821801 is an equidigital number, since it uses as much as digits as its factorization.

821801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 821801 is about 906.5324042747. The cubic root of 821801 is about 93.6674912578.

Adding to 821801 its reverse (108128), we get a palindrome (929929).

The spelling of 821801 in words is "eight hundred twenty-one thousand, eight hundred one".