811021919 has 4 divisors (see below), whose sum is σ = 813908400. Its totient is φ = 808135440.

The previous prime is 811021909. The next prime is 811021921. The reversal of 811021919 is 919120118.

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 811021919 - 2⁴ = 811021903 is a prime.

It is a super-2 number, since 2×811021919² = 1315513106196885122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811021909) 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, 1442819 + ... + 1443380.

It is an arithmetic number, because the mean of its divisors is an integer number (203477100).

Almost surely, 2^811021919 is an apocalyptic number.

811021919 is a deficient number, since it is larger than the sum of its proper divisors (2886481).

811021919 is a wasteful number, since it uses less digits than its factorization.

811021919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2886480.

The product of its (nonzero) digits is 1296, while the sum is 32.

The square root of 811021919 is about 28478.4465692917. The cubic root of 811021919 is about 932.5616043175.

The spelling of 811021919 in words is "eight hundred eleven million, twenty-one thousand, nine hundred nineteen".