866800082636821 has 4 divisors (see below), whose sum is σ = 868919398242700. Its totient is φ = 864680767030944.

The previous prime is 866800082636797. The next prime is 866800082636857. The reversal of 866800082636821 is 128636280008668.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 773423131556196 + 93376951080625 = 27810486^2 + 9663175^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866800082636821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866800082636861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1059657802326 + ... + 1059657803143.

It is an arithmetic number, because the mean of its divisors is an integer number (217229849560675).

Almost surely, 2^{866800082636821} is an apocalyptic number.

It is an amenable number.

866800082636821 is a deficient number, since it is larger than the sum of its proper divisors (2119315605879).

866800082636821 is a wasteful number, since it uses less digits than its factorization.

866800082636821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2119315605878.

The product of its (nonzero) digits is 63700992, while the sum is 64.

The spelling of 866800082636821 in words is "eight hundred sixty-six trillion, eight hundred billion, eighty-two million, six hundred thirty-six thousand, eight hundred twenty-one".