813636666 has 48 divisors (see below), whose sum is σ = 1796177448. Its totient is φ = 266112000.

The previous prime is 813636647. The next prime is 813636671. The reversal of 813636666 is 666636318.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 31036041 + 782600625 = 5571^2 + 27975^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 676866 + ... + 678066.

Almost surely, 2^813636666 is an apocalyptic number.

813636666 is an abundant number, since it is smaller than the sum of its proper divisors (982540782).

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

813636666 is a wasteful number, since it uses less digits than its factorization.

813636666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1887 (or 1884 counting only the distinct ones).

The product of its digits is 559872, while the sum is 45.

The square root of 813636666 is about 28524.3170996257. The cubic root of 813636666 is about 933.5627268070.

The spelling of 813636666 in words is "eight hundred thirteen million, six hundred thirty-six thousand, six hundred sixty-six".