811557864 has 96 divisors (see below), whose sum is σ = 2388302280. Its totient is φ = 247468032.

The previous prime is 811557833. The next prime is 811557869. The reversal of 811557864 is 468755118.

811557864 is a `hidden beast` number, since 8 + 1 + 15 + 578 + 64 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 356076900 + 455480964 = 18870^2 + 21342^2 .

It is not an unprimeable number, because it can be changed into a prime (811557869) 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, 101932 + ... + 109604.

Almost surely, 2^811557864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 811557864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1194151140).

811557864 is an abundant number, since it is smaller than the sum of its proper divisors (1576744416).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

811557864 is a wasteful number, since it uses less digits than its factorization.

811557864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7811 (or 7804 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The square root of 811557864 is about 28487.8546752822. The cubic root of 811557864 is about 932.7669796445.

The spelling of 811557864 in words is "eight hundred eleven million, five hundred fifty-seven thousand, eight hundred sixty-four".