820655661043821 has 16 divisors (see below), whose sum is σ = 1094546063764800. Its totient is φ = 546934542240768.

The previous prime is 820655661043783. The next prime is 820655661043853. The reversal of 820655661043821 is 128340166556028.

It is not a de Polignac number, because 820655661043821 - 2¹³ = 820655661035629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820655661543821) 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 15 ways as a sum of consecutive naturals, for example, 122941410 + ... + 129444588.

It is an arithmetic number, because the mean of its divisors is an integer number (68409128985300).

Almost surely, 2^{820655661043821} is an apocalyptic number.

It is an amenable number.

820655661043821 is a deficient number, since it is larger than the sum of its proper divisors (273890402720979).

820655661043821 is a wasteful number, since it uses less digits than its factorization.

820655661043821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6516188.

The product of its (nonzero) digits is 16588800, while the sum is 57.

The spelling of 820655661043821 in words is "eight hundred twenty trillion, six hundred fifty-five billion, six hundred sixty-one million, forty-three thousand, eight hundred twenty-one".