21621344066145 has 12 divisors (see below), whose sum is σ = 37476996381396. Its totient is φ = 11531383501920.

The previous prime is 21621344066117. The next prime is 21621344066207. The reversal of 21621344066145 is 54166044312612.

21621344066145 is a `hidden beast` number, since 2 + 1 + 6 + 2 + 1 + 3 + 440 + 66 + 145 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3987114394176 + 17634229671969 = 1996776^2 + 4199313^2 .

It is not a de Polignac number, because 21621344066145 - 2²⁰ = 21621343017569 is a prime.

It is a super-2 number, since 2×21621344066145² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 480474312581 = 21621344066145 / (2 + 1 + 6 + 2 + 1 + 3 + 4 + 4 + 0 + 6 + 6 + 1 + 4 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 21621344066145.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 240237156246 + ... + 240237156335.

It is an arithmetic number, because the mean of its divisors is an integer number (3123083031783).

Almost surely, 2^{21621344066145} is an apocalyptic number.

It is an amenable number.

21621344066145 is a deficient number, since it is larger than the sum of its proper divisors (15855652315251).

21621344066145 is a wasteful number, since it uses less digits than its factorization.

21621344066145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 480474312592 (or 480474312589 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 45.

Adding to 21621344066145 its reverse (54166044312612), we get a palindrome (75787388378757).

The spelling of 21621344066145 in words is "twenty-one trillion, six hundred twenty-one billion, three hundred forty-four million, sixty-six thousand, one hundred forty-five".