21366315653 has 8 divisors (see below), whose sum is σ = 21406328568. Its totient is φ = 21326329024.

The previous prime is 21366315631. The next prime is 21366315661. The reversal of 21366315653 is 35651366312.

It can be written as a sum of positive squares in 4 ways, for example, as 10811424484 + 10554891169 = 103978^2 + 102737^2 .

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 21366315653 - 2²⁴ = 21349538437 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21366315653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366315053) 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, 2387375 + ... + 2396307.

It is an arithmetic number, because the mean of its divisors is an integer number (2675791071).

Almost surely, 2^21366315653 is an apocalyptic number.

It is an amenable number.

21366315653 is a deficient number, since it is larger than the sum of its proper divisors (40012915).

21366315653 is an equidigital number, since it uses as much as digits as its factorization.

21366315653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13143.

The product of its digits is 291600, while the sum is 41.

The spelling of 21366315653 in words is "twenty-one billion, three hundred sixty-six million, three hundred fifteen thousand, six hundred fifty-three".