811687813 has 8 divisors (see below), whose sum is σ = 820348056. Its totient is φ = 803040000.

The previous prime is 811687741. The next prime is 811687817. The reversal of 811687813 is 318786118.

It can be written as a sum of positive squares in 4 ways, for example, as 275626404 + 536061409 = 16602^2 + 23153^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 811687813 - 2²⁵ = 778133381 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 811687813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811687817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191113 + ... + 195313.

It is an arithmetic number, because the mean of its divisors is an integer number (102543507).

Almost surely, 2^811687813 is an apocalyptic number.

It is an amenable number.

811687813 is a deficient number, since it is larger than the sum of its proper divisors (8660243).

811687813 is a wasteful number, since it uses less digits than its factorization.

811687813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6215.

The product of its digits is 64512, while the sum is 43.

The square root of 811687813 is about 28490.1353629638. The cubic root of 811687813 is about 932.8167627725.

The spelling of 811687813 in words is "eight hundred eleven million, six hundred eighty-seven thousand, eight hundred thirteen".