16555555821 has 8 divisors (see below), whose sum is σ = 25227513664. Its totient is φ = 9460317600.

The previous prime is 16555555811. The next prime is 16555555829. The reversal of 16555555821 is 12855555561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 16555555821 - 2¹³ = 16555547629 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16555555829) 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 7 ways as a sum of consecutive naturals, for example, 394179880 + ... + 394179921.

It is an arithmetic number, because the mean of its divisors is an integer number (3153439208).

Almost surely, 2^16555555821 is an apocalyptic number.

It is an amenable number.

16555555821 is a deficient number, since it is larger than the sum of its proper divisors (8671957843).

16555555821 is an equidigital number, since it uses as much as digits as its factorization.

16555555821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 788359811.

The product of its digits is 1500000, while the sum is 48.

The spelling of 16555555821 in words is "sixteen billion, five hundred fifty-five million, five hundred fifty-five thousand, eight hundred twenty-one".