811105021 has 4 divisors (see below), whose sum is σ = 814470844. Its totient is φ = 807739200.

The previous prime is 811105007. The next prime is 811105063. The reversal of 811105021 is 120501118.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 746928900 + 64176121 = 27330^2 + 8011^2 .

It is a cyclic number.

It is not a de Polignac number, because 811105021 - 2⁵ = 811104989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 811105021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811100021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1682550 + ... + 1683031.

It is an arithmetic number, because the mean of its divisors is an integer number (203617711).

Almost surely, 2^811105021 is an apocalyptic number.

It is an amenable number.

811105021 is a deficient number, since it is larger than the sum of its proper divisors (3365823).

811105021 is a wasteful number, since it uses less digits than its factorization.

811105021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3365822.

The product of its (nonzero) digits is 80, while the sum is 19.

The square root of 811105021 is about 28479.9055651524. The cubic root of 811105021 is about 932.5934551162.

Adding to 811105021 its reverse (120501118), we get a palindrome (931606139).

The spelling of 811105021 in words is "eight hundred eleven million, one hundred five thousand, twenty-one".