821869 has 2 divisors, whose sum is σ = 821870. Its totient is φ = 821868.

The previous prime is 821861. The next prime is 821879. The reversal of 821869 is 968128.

821869 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 619369 + 202500 = 787^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 821869 - 2³ = 821861 is a prime.

It is a super-3 number, since 3×821869³ = 1665440239514333727, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410934 + 410935.

It is an arithmetic number, because the mean of its divisors is an integer number (410935).

2⁸²¹⁸⁶⁹ is an apocalyptic number.

It is an amenable number.

821869 is a deficient number, since it is larger than the sum of its proper divisors (1).

821869 is an equidigital number, since it uses as much as digits as its factorization.

821869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 34.

The square root of 821869 is about 906.5699090528. The cubic root of 821869 is about 93.6700746949.

The spelling of 821869 in words is "eight hundred twenty-one thousand, eight hundred sixty-nine".