850821 has 4 divisors (see below), whose sum is σ = 1134432. Its totient is φ = 567212.

The previous prime is 850807. The next prime is 850823. The reversal of 850821 is 128058.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 850821 - 2¹⁷ = 719749 is a prime.

It is a D-number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 850791 and 850800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (850823) 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, 141801 + ... + 141806.

It is an arithmetic number, because the mean of its divisors is an integer number (283608).

2⁸⁵⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

850821 is a deficient number, since it is larger than the sum of its proper divisors (283611).

850821 is a wasteful number, since it uses less digits than its factorization.

850821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283610.

The product of its (nonzero) digits is 640, while the sum is 24.

The square root of 850821 is about 922.3995880311. The cubic root of 850821 is about 94.7573122271.

Adding to 850821 its reverse (128058), we get a palindrome (978879).

The spelling of 850821 in words is "eight hundred fifty thousand, eight hundred twenty-one".