21115515553165 has 64 divisors (see below), whose sum is σ = 28474807495680. Its totient is φ = 14896677565440.

The previous prime is 21115515553151. The next prime is 21115515553177. The reversal of 21115515553165 is 56135551551112.

It is not a de Polignac number, because 21115515553165 - 2¹⁵ = 21115515520397 is a prime.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 2404130364 + ... + 2404139146.

It is an arithmetic number, because the mean of its divisors is an integer number (444918867120).

Almost surely, 2^{21115515553165} is an apocalyptic number.

It is an amenable number.

21115515553165 is a deficient number, since it is larger than the sum of its proper divisors (7359291942515).

21115515553165 is a wasteful number, since it uses less digits than its factorization.

21115515553165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12262.

The product of its digits is 562500, while the sum is 46.

The spelling of 21115515553165 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred fifty-three thousand, one hundred sixty-five".