811948021 has 4 divisors (see below), whose sum is σ = 812225932. Its totient is φ = 811670112.

The previous prime is 811948019. The next prime is 811948031. The reversal of 811948021 is 120849118.

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 648466225 + 163481796 = 25465^2 + 12786^2 .

It is a cyclic number.

It is not a de Polignac number, because 811948021 - 2¹ = 811948019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811948031) 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, 134526 + ... + 140431.

It is an arithmetic number, because the mean of its divisors is an integer number (203056483).

Almost surely, 2^811948021 is an apocalyptic number.

It is an amenable number.

811948021 is a deficient number, since it is larger than the sum of its proper divisors (277911).

811948021 is a wasteful number, since it uses less digits than its factorization.

811948021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277910.

The product of its (nonzero) digits is 4608, while the sum is 34.

The square root of 811948021 is about 28494.7016303031. The cubic root of 811948021 is about 932.9164318191.

The spelling of 811948021 in words is "eight hundred eleven million, nine hundred forty-eight thousand, twenty-one".