811561986 has 24 divisors (see below), whose sum is σ = 1778144940. Its totient is φ = 267480576.

The previous prime is 811561943. The next prime is 811562027. The reversal of 811561986 is 689165118.

811561986 is a `hidden beast` number, since 8 + 1 + 1 + 561 + 9 + 86 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 799136361 + 12425625 = 28269^2 + 3525^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 251695 + ... + 254898.

Almost surely, 2^811561986 is an apocalyptic number.

811561986 is an abundant number, since it is smaller than the sum of its proper divisors (966582954).

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

811561986 is a wasteful number, since it uses less digits than its factorization.

811561986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506690 (or 506687 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 811561986 is about 28487.9270218105. The cubic root of 811561986 is about 932.7685588537.

The spelling of 811561986 in words is "eight hundred eleven million, five hundred sixty-one thousand, nine hundred eighty-six".