21216034255221 has 48 divisors (see below), whose sum is σ = 34945208691120. Its totient is φ = 12287614648320.

The previous prime is 21216034255147. The next prime is 21216034255223. The reversal of 21216034255221 is 12255243061212.

21216034255221 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 6 + 0 + 3 + 425 + 5 + 221 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 3946698756900 + 17269335498321 = 1986630^2 + 4155639^2 .

It is not a de Polignac number, because 21216034255221 - 2¹¹ = 21216034253173 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21216034255223) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 66514165 + ... + 66832373.

It is an arithmetic number, because the mean of its divisors is an integer number (728025181065).

Almost surely, 2^{21216034255221} is an apocalyptic number.

It is an amenable number.

21216034255221 is a deficient number, since it is larger than the sum of its proper divisors (13729174435899).

21216034255221 is a wasteful number, since it uses less digits than its factorization.

21216034255221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351766 (or 351763 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 21216034255221 in words is "twenty-one trillion, two hundred sixteen billion, thirty-four million, two hundred fifty-five thousand, two hundred twenty-one".