821011 has 4 divisors (see below), whose sum is σ = 828792. Its totient is φ = 813232.

The previous prime is 821003. The next prime is 821027. The reversal of 821011 is 110128.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 821011 - 2³ = 821003 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 820982 and 821000.

It is not an unprimeable number, because it can be changed into a prime (821081) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3730 + ... + 3943.

It is an arithmetic number, because the mean of its divisors is an integer number (207198).

2⁸²¹⁰¹¹ is an apocalyptic number.

821011 is a deficient number, since it is larger than the sum of its proper divisors (7781).

821011 is a wasteful number, since it uses less digits than its factorization.

821011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7780.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 821011 is about 906.0965732194. The cubic root of 821011 is about 93.6374673460.

Adding to 821011 its reverse (110128), we get a palindrome (931139).

The spelling of 821011 in words is "eight hundred twenty-one thousand, eleven".