681655264821 has 12 divisors (see below), whose sum is σ = 1027422428448. Its totient is φ = 434678719464.

The previous prime is 681655264819. The next prime is 681655264919. The reversal of 681655264821 is 128462556186.

681655264821 is a `hidden beast` number, since 6 + 8 + 1 + 6 + 552 + 6 + 4 + 82 + 1 = 666.

It is not a de Polignac number, because 681655264821 - 2¹ = 681655264819 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681655264421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1646510095 + ... + 1646510508.

It is an arithmetic number, because the mean of its divisors is an integer number (85618535704).

Almost surely, 2^681655264821 is an apocalyptic number.

It is an amenable number.

681655264821 is a deficient number, since it is larger than the sum of its proper divisors (345767163627).

681655264821 is a wasteful number, since it uses less digits than its factorization.

681655264821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3293020632 (or 3293020629 counting only the distinct ones).

The product of its digits is 5529600, while the sum is 54.

The spelling of 681655264821 in words is "six hundred eighty-one billion, six hundred fifty-five million, two hundred sixty-four thousand, eight hundred twenty-one".