21183929209 has 3 divisors (see below), whose sum is σ = 21184074757. Its totient is φ = 21183783662.

The previous prime is 21183929201. The next prime is 21183929227. The reversal of 21183929209 is 90292938112.

The square root of 21183929209 is 145547.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 21183929209 - 2³ = 21183929201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21183929201) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 72774 + ... + 218320.

Almost surely, 2^21183929209 is an apocalyptic number.

21183929209 is the 145547-th square number.

21183929209 is the 72774-th centered octagonal number.

It is an amenable number.

21183929209 is a deficient number, since it is larger than the sum of its proper divisors (145548).

21183929209 is an frugal number, since it uses more digits than its factorization.

21183929209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291094 (or 145547 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 46.

The spelling of 21183929209 in words is "twenty-one billion, one hundred eighty-three million, nine hundred twenty-nine thousand, two hundred nine".