21660353662253 has 2 divisors, whose sum is σ = 21660353662254. Its totient is φ = 21660353662252.

The previous prime is 21660353662247. The next prime is 21660353662271. The reversal of 21660353662253 is 35226635306612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17087864260009 + 4572489402244 = 4133747^2 + 2138338^2 .

It is a cyclic number.

It is not a de Polignac number, because 21660353662253 - 2²⁰ = 21660352613677 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21660353652253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830176831126 + 10830176831127.

It is an arithmetic number, because the mean of its divisors is an integer number (10830176831127).

Almost surely, 2^{21660353662253} is an apocalyptic number.

It is an amenable number.

21660353662253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21660353662253 is an equidigital number, since it uses as much as digits as its factorization.

21660353662253 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6998400, while the sum is 50.

Adding to 21660353662253 its reverse (35226635306612), we get a palindrome (56886988968865).

The spelling of 21660353662253 in words is "twenty-one trillion, six hundred sixty billion, three hundred fifty-three million, six hundred sixty-two thousand, two hundred fifty-three".