21160665653 has 4 divisors (see below), whose sum is σ = 21202239180. Its totient is φ = 21119092128.

The previous prime is 21160665637. The next prime is 21160665661. The reversal of 21160665653 is 35656606112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7355120644 + 13805545009 = 85762^2 + 117497^2 .

It is a cyclic number.

It is not a de Polignac number, because 21160665653 - 2⁴ = 21160665637 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 21160665653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21160665613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20786000 + ... + 20787017.

It is an arithmetic number, because the mean of its divisors is an integer number (5300559795).

Almost surely, 2^21160665653 is an apocalyptic number.

It is an amenable number.

21160665653 is a deficient number, since it is larger than the sum of its proper divisors (41573527).

21160665653 is an equidigital number, since it uses as much as digits as its factorization.

21160665653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41573526.

The product of its (nonzero) digits is 194400, while the sum is 41.

The spelling of 21160665653 in words is "twenty-one billion, one hundred sixty million, six hundred sixty-five thousand, six hundred fifty-three".