21165055666155 has 24 divisors (see below), whose sum is σ = 36686923573248. Its totient is φ = 11287775200896.

The previous prime is 21165055666091. The next prime is 21165055666193. The reversal of 21165055666155 is 55166655056112.

It is not a de Polignac number, because 21165055666155 - 2⁶ = 21165055666091 is a prime.

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, 3275122 + ... + 7283991.

It is an arithmetic number, because the mean of its divisors is an integer number (1528621815552).

Almost surely, 2^{21165055666155} is an apocalyptic number.

21165055666155 is a deficient number, since it is larger than the sum of its proper divisors (15521867907093).

21165055666155 is a wasteful number, since it uses less digits than its factorization.

21165055666155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10603667 (or 10603664 counting only the distinct ones).

The product of its (nonzero) digits is 8100000, while the sum is 54.

The spelling of 21165055666155 in words is "twenty-one trillion, one hundred sixty-five billion, fifty-five million, six hundred sixty-six thousand, one hundred fifty-five".