21992000209 has 9 divisors (see below), whose sum is σ = 22547706961. Its totient is φ = 21449678080.

The previous prime is 21992000201. The next prime is 21992000263. The reversal of 21992000209 is 90200029912.

The square root of 21992000209 is 148297.

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 20171100625 + 1820899584 = 142025^2 + 42672^2 .

It is not a de Polignac number, because 21992000209 - 2³ = 21992000201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21992000201) 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, 6078369 + ... + 6081985.

Almost surely, 2^21992000209 is an apocalyptic number.

21992000209 is the 148297-th square number.

21992000209 is the 74149-th centered octagonal number.

It is an amenable number.

21992000209 is a deficient number, since it is larger than the sum of its proper divisors (555706752).

21992000209 is an frugal number, since it uses more digits than its factorization.

21992000209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7316 (or 3658 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 34.

The spelling of 21992000209 in words is "twenty-one billion, nine hundred ninety-two million, two hundred nine", and thus it is an aban number.