820931 has 4 divisors (see below), whose sum is σ = 822864. Its totient is φ = 819000.

The previous prime is 820927. The next prime is 820957. The reversal of 820931 is 139028.

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 820931 - 2² = 820927 is a prime.

It is a super-4 number, since 4×820931⁴ (a number of 25 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 820897 and 820906.

It is not an unprimeable number, because it can be changed into a prime (820901) 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, 20 + ... + 1281.

It is an arithmetic number, because the mean of its divisors is an integer number (205716).

2⁸²⁰⁹³¹ is an apocalyptic number.

820931 is a deficient number, since it is larger than the sum of its proper divisors (1933).

820931 is a wasteful number, since it uses less digits than its factorization.

820931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1932.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 820931 is about 906.0524267392. The cubic root of 820931 is about 93.6344258761.

Adding to 820931 its reverse (139028), we get a palindrome (959959).

The spelling of 820931 in words is "eight hundred twenty thousand, nine hundred thirty-one".