21668534055 has 24 divisors (see below), whose sum is σ = 42924334752. Its totient is φ = 9905615424.

The previous prime is 21668534029. The next prime is 21668534087. The reversal of 21668534055 is 55043586612.

21668534055 is a `hidden beast` number, since 2 + 1 + 6 + 68 + 534 + 0 + 55 = 666.

It is not a de Polignac number, because 21668534055 - 2¹² = 21668529959 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21668534055.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34394184 + ... + 34394813.

It is an arithmetic number, because the mean of its divisors is an integer number (1788513948).

Almost surely, 2^21668534055 is an apocalyptic number.

21668534055 is a deficient number, since it is larger than the sum of its proper divisors (21255800697).

21668534055 is a wasteful number, since it uses less digits than its factorization.

21668534055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68789015 (or 68789012 counting only the distinct ones).

The product of its (nonzero) digits is 864000, while the sum is 45.

The spelling of 21668534055 in words is "twenty-one billion, six hundred sixty-eight million, five hundred thirty-four thousand, fifty-five".