21556678865455 has 8 divisors (see below), whose sum is σ = 26498941825104. Its totient is φ = 16824724968000.

The previous prime is 21556678865443. The next prime is 21556678865497. The reversal of 21556678865455 is 55456887665512.

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

It is not a de Polignac number, because 21556678865455 - 2¹⁹ = 21556678341167 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52577265321 + ... + 52577265730.

It is an arithmetic number, because the mean of its divisors is an integer number (3312367728138).

Almost surely, 2^{21556678865455} is an apocalyptic number.

21556678865455 is a deficient number, since it is larger than the sum of its proper divisors (4942262959649).

21556678865455 is a wasteful number, since it uses less digits than its factorization.

21556678865455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105154531097.

The product of its digits is 2419200000, while the sum is 73.

The spelling of 21556678865455 in words is "twenty-one trillion, five hundred fifty-six billion, six hundred seventy-eight million, eight hundred sixty-five thousand, four hundred fifty-five".