21660550709 has 16 divisors (see below), whose sum is σ = 25119578880. Its totient is φ = 18293022720.

The previous prime is 21660550699. The next prime is 21660550757. The reversal of 21660550709 is 90705506612.

It is not a de Polignac number, because 21660550709 - 2¹⁶ = 21660485173 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660552709) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 816437 + ... + 842549.

It is an arithmetic number, because the mean of its divisors is an integer number (1569973680).

Almost surely, 2^21660550709 is an apocalyptic number.

It is an amenable number.

21660550709 is a deficient number, since it is larger than the sum of its proper divisors (3459028171).

21660550709 is a wasteful number, since it uses less digits than its factorization.

21660550709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27860.

The product of its (nonzero) digits is 113400, while the sum is 41.

The spelling of 21660550709 in words is "twenty-one billion, six hundred sixty million, five hundred fifty thousand, seven hundred nine".