21660535151665 has 64 divisors (see below), whose sum is σ = 26765846323200. Its totient is φ = 16821782175744.

The previous prime is 21660535151659. The next prime is 21660535151669. The reversal of 21660535151665 is 56615153506612.

It is a cyclic number.

It is not a de Polignac number, because 21660535151665 - 2¹³ = 21660535143473 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21660535151669) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 15115515789 + ... + 15115517221.

It is an arithmetic number, because the mean of its divisors is an integer number (418216348800).

Almost surely, 2^{21660535151665} is an apocalyptic number.

It is an amenable number.

21660535151665 is a deficient number, since it is larger than the sum of its proper divisors (5105311171535).

21660535151665 is a wasteful number, since it uses less digits than its factorization.

21660535151665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3226.

The product of its (nonzero) digits is 4860000, while the sum is 52.

The spelling of 21660535151665 in words is "twenty-one trillion, six hundred sixty billion, five hundred thirty-five million, one hundred fifty-one thousand, six hundred sixty-five".