21660550264261 has 8 divisors (see below), whose sum is σ = 21787922874744. Its totient is φ = 21533202563520.

The previous prime is 21660550264247. The next prime is 21660550264289. The reversal of 21660550264261 is 16246205506612.

It can be written as a sum of positive squares in 4 ways, for example, as 8487142092900 + 13173408171361 = 2913270^2 + 3629519^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21660550264261 - 2²⁹ = 21660013393349 is a prime.

It is a super-2 number, since 2×21660550264261² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660550264211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4481766 + ... + 7962871.

It is an arithmetic number, because the mean of its divisors is an integer number (2723490359343).

Almost surely, 2^{21660550264261} is an apocalyptic number.

It is an amenable number.

21660550264261 is a deficient number, since it is larger than the sum of its proper divisors (127372610483).

21660550264261 is a wasteful number, since it uses less digits than its factorization.

21660550264261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12454871.

The product of its (nonzero) digits is 1036800, while the sum is 46.

The spelling of 21660550264261 in words is "twenty-one trillion, six hundred sixty billion, five hundred fifty million, two hundred sixty-four thousand, two hundred sixty-one".