21593563209 has 6 divisors (see below), whose sum is σ = 31190702426. Its totient is φ = 14395708800.

The previous prime is 21593563157. The next prime is 21593563231. The reversal of 21593563209 is 90236539512.

21593563209 is a `hidden beast` number, since 2 + 1 + 5 + 9 + 3 + 5 + 632 + 0 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21040372809 + 553190400 = 145053^2 + 23520^2 .

It is not a de Polignac number, because 21593563209 - 2¹³ = 21593555017 is a prime.

It is a super-2 number, since 2×21593563209² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21593565209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1199642392 + ... + 1199642409.

Almost surely, 2^21593563209 is an apocalyptic number.

It is an amenable number.

21593563209 is a deficient number, since it is larger than the sum of its proper divisors (9597139217).

21593563209 is a wasteful number, since it uses less digits than its factorization.

21593563209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2399284807 (or 2399284804 counting only the distinct ones).

The product of its (nonzero) digits is 437400, while the sum is 45.

The spelling of 21593563209 in words is "twenty-one billion, five hundred ninety-three million, five hundred sixty-three thousand, two hundred nine".