21843953209 has 9 divisors (see below), whose sum is σ = 23655592173. Its totient is φ = 20161875552.

The previous prime is 21843953189. The next prime is 21843953221. The reversal of 21843953209 is 90235934812.

The square root of 21843953209 is 147797.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 2083466025 + 19760487184 = 45645^2 + 140572^2 .

It is not a de Polignac number, because 21843953209 - 2¹⁷ = 21843822137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21843953909) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1915677 + ... + 1927045.

Almost surely, 2^21843953209 is an apocalyptic number.

21843953209 is the 147797-th square number.

21843953209 is the 73899-th centered octagonal number.

It is an amenable number.

21843953209 is a deficient number, since it is larger than the sum of its proper divisors (1811638964).

21843953209 is an frugal number, since it uses more digits than its factorization.

21843953209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22764 (or 11382 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 46.

The spelling of 21843953209 in words is "twenty-one billion, eight hundred forty-three million, nine hundred fifty-three thousand, two hundred nine".