820811961 has 24 divisors (see below), whose sum is σ = 1232431200. Its totient is φ = 545916672.

The previous prime is 820811947. The next prime is 820811977. The reversal of 820811961 is 169118028.

820811961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 820811961 - 2⁶ = 820811897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (820811921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 105346 + ... + 112868.

It is an arithmetic number, because the mean of its divisors is an integer number (51351300).

Almost surely, 2^820811961 is an apocalyptic number.

820811961 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

820811961 is a deficient number, since it is larger than the sum of its proper divisors (411619239).

820811961 is an equidigital number, since it uses as much as digits as its factorization.

820811961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7987 (or 7975 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 36.

The square root of 820811961 is about 28649.8160727080. The cubic root of 820811961 is about 936.2989984119.

Adding to 820811961 its reverse (169118028), we get a palindrome (989929989).

The spelling of 820811961 in words is "eight hundred twenty million, eight hundred eleven thousand, nine hundred sixty-one".