21905602009 has 4 divisors (see below), whose sum is σ = 22009420240. Its totient is φ = 21801783780.

The previous prime is 21905602007. The next prime is 21905602027. The reversal of 21905602009 is 90020650912.

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 21905602009 - 2¹ = 21905602007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21905602003) 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, 51908799 + ... + 51909220.

It is an arithmetic number, because the mean of its divisors is an integer number (5502355060).

Almost surely, 2^21905602009 is an apocalyptic number.

It is an amenable number.

21905602009 is a deficient number, since it is larger than the sum of its proper divisors (103818231).

21905602009 is a wasteful number, since it uses less digits than its factorization.

21905602009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103818230.

The product of its (nonzero) digits is 9720, while the sum is 34.

The spelling of 21905602009 in words is "twenty-one billion, nine hundred five million, six hundred two thousand, nine".