21909380985 has 80 divisors (see below), whose sum is σ = 41446004160. Its totient is φ = 11042075520.

The previous prime is 21909380981. The next prime is 21909381007. The reversal of 21909380985 is 58908390912.

It is not a de Polignac number, because 21909380985 - 2² = 21909380981 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21909380981) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 3236214 + ... + 3242976.

It is an arithmetic number, because the mean of its divisors is an integer number (518075052).

Almost surely, 2^21909380985 is an apocalyptic number.

It is an amenable number.

21909380985 is a deficient number, since it is larger than the sum of its proper divisors (19536623175).

21909380985 is a wasteful number, since it uses less digits than its factorization.

21909380985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7220 (or 7211 counting only the distinct ones).

The product of its (nonzero) digits is 1399680, while the sum is 54.

The spelling of 21909380985 in words is "twenty-one billion, nine hundred nine million, three hundred eighty thousand, nine hundred eighty-five".