21665448053 has 4 divisors (see below), whose sum is σ = 21665859168. Its totient is φ = 21665036940.

The previous prime is 21665448043. The next prime is 21665448059. The reversal of 21665448053 is 35084456612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21665448053 - 2⁴ = 21665448037 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21665447995 and 21665448013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665448059) 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, 112451 + ... + 236592.

It is an arithmetic number, because the mean of its divisors is an integer number (5416464792).

Almost surely, 2^21665448053 is an apocalyptic number.

It is an amenable number.

21665448053 is a deficient number, since it is larger than the sum of its proper divisors (411115).

21665448053 is an equidigital number, since it uses as much as digits as its factorization.

21665448053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 411114.

The product of its (nonzero) digits is 691200, while the sum is 44.

The spelling of 21665448053 in words is "twenty-one billion, six hundred sixty-five million, four hundred forty-eight thousand, fifty-three".