21805968097 has 4 divisors (see below), whose sum is σ = 21998941380. Its totient is φ = 21612994816.

The previous prime is 21805968031. The next prime is 21805968101. The reversal of 21805968097 is 79086950812.

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 9192207376 + 12613760721 = 95876^2 + 112311^2 .

It is a cyclic number.

It is not a de Polignac number, because 21805968097 - 2¹⁹ = 21805443809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21805968497) 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, 96486472 + ... + 96486697.

It is an arithmetic number, because the mean of its divisors is an integer number (5499735345).

Almost surely, 2^21805968097 is an apocalyptic number.

It is an amenable number.

21805968097 is a deficient number, since it is larger than the sum of its proper divisors (192973283).

21805968097 is a wasteful number, since it uses less digits than its factorization.

21805968097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192973282.

The product of its (nonzero) digits is 2177280, while the sum is 55.

The spelling of 21805968097 in words is "twenty-one billion, eight hundred five million, nine hundred sixty-eight thousand, ninety-seven".